Support multiple keybindings to a single command (#70)

## Brief description of changes
- support multiple keybindings to a single command by specifying either **a key string** or **an array of key strings** in the config file
- add `[back]` button to the application's footer 

## Breaking changes
- modify the default shortcuts for
  - `global_keymap.quit`
  -  `global_keymap.goto_previous_view`
  -  `global_keymap.goto_search_view`
  -  `edit_keymap.move_cursor_left`
  -  `edit_keymap.move_cursor_right`
  -  `edit_keymap.move_cursor_to_begin`
  -  `edit_keymap.move_cursor_to_end`   

10 files changed, 339 insertions, 262 deletions

diff --git a/README.md b/README.md
index 93e65e3..f0835ab 100644
--- a/README.md
+++ b/README.md
@@ -140,27 +140,27 @@ For more information about configuring the key mapping or defining custom shortc
 
 ### Global key shortcuts
 
-| Command                 | Description             | Default Shortcut |
-| ----------------------- | ----------------------- | ---------------- |
-| `open_help_dialog`      | Open the help dialog    | `?`              |
-| `close_dialog`          | Close a dialog          | `esc`            |
-| `quit`                  | Quit the application    | `C-q`            |
-| `goto_previous_view`    | Go to the previous view | `C-p`            |
-| `goto_search_view`      | Go to search view       | `C-s`            |
-| `goto_front_page_view`  | Go to front page view   | `F1`             |
-| `goto_all_stories_view` | Go to all stories view  | `F2`             |
-| `goto_ask_hn_view`      | Go to ask HN view       | `F3`             |
-| `goto_show_hn_view`     | Go to show HN view      | `F4`             |
-| `goto_jobs_view`        | Go to jobs view         | `F5`             |
+| Command                 | Description             | Default Shortcut   |
+| ----------------------- | ----------------------- | ------------------ |
+| `open_help_dialog`      | Open the help dialog    | `?`                |
+| `close_dialog`          | Close a dialog          | `esc`              |
+| `quit`                  | Quit the application    | `[q, C-c]`         |
+| `goto_previous_view`    | Go to the previous view | `[backspace, C-p]` |
+| `goto_search_view`      | Go to search view       | `[/, C-s]`         |
+| `goto_front_page_view`  | Go to front page view   | `F1`               |
+| `goto_all_stories_view` | Go to all stories view  | `F2`               |
+| `goto_ask_hn_view`      | Go to ask HN view       | `F3`               |
+| `goto_show_hn_view`     | Go to show HN view      | `F4`               |
+| `goto_jobs_view`        | Go to jobs view         | `F5`               |
 
 ### Edit key shortcuts
 
 | Command                | Description                      | Default Shortcut |
 | ---------------------- | -------------------------------- | ---------------- |
-| `move_cursor_left`     | Move cursor to left              | `left`           |
-| `move_cursor_right`    | Move cursor to right             | `right`          |
-| `move_cursor_to_begin` | Move cursor to the begin of line | `home`           |
-| `move_cursor_to_end`   | Move cursor to the end of line   | `end`            |
+| `move_cursor_left`     | Move cursor to left              | `[left, C-b]`    |
+| `move_cursor_right`    | Move cursor to right             | `[right, C-f]`   |
+| `move_cursor_to_begin` | Move cursor to the begin of line | `[home, C-a]`    |
+| `move_cursor_to_end`   | Move cursor to the end of line   | `[end, C-e]`     |
 | `backward_delete_char` | Delete backward a character      | `backspace`      |
 
 ### Key shortcuts for each `View`
@@ -208,26 +208,26 @@ For more information about configuring the key mapping or defining custom shortc
 
 #### Comment View shortcuts
 
-| Command                     | Description                                                          | Default Shortcut |
-| --------------------------- | -------------------------------------------------------------------- | ---------------- |
-| `next_comment`              | Focus the next comment                                               | `j`              |
-| `prev_comment`              | Focus the previous comment                                           | `k`              |
-| `next_leq_level_comment`    | Focus the next comment with smaller or equal level                   | `l`              |
-| `prev_leq_level_comment`    | Focus the previous comment with smaller or equal level               | `h`              |
-| `next_top_level_comment`    | Focus the next top level comment                                     | `n`              |
-| `prev_top_level_comment`    | Focus the previous top level comment                                 | `p`              |
-| `parent_comment`            | Focus the parent comment (if exists)                                 | `u`              |
-| `toggle_collapse_comment`   | Toggle collapsing the focused comment                                | `tab`            |
-| `up`                        | Scroll up                                                            | `up`             |
-| `down`                      | Scroll down                                                          | `down`           |
-| `page_up`                   | Scroll up half a page                                                | `page_up`        |
-| `page_down`                 | Scroll down half a page                                              | `page_down`      |
-| `open_article_in_browser`   | Open in browser the article associated with the discussed story      | `o`              |
-| `open_link_in_article_view` | Open in article view the article associated with the discussed story | `O`              |
-| `open_story_in_browser`     | Open in browser the discussed story                                  | `s`              |
-| `open_comment_in_browser`   | Open in browser the focused comment                                  | `c`              |
-| `open_link_in_browser`      | Open in browser the {link_id}-th link in the focused comment         | `{link_id} f`    |
-| `open_link_in_article_view` | Open in article view the {link_id}-th link in the focused comment    | `{link_id} F`    |
+| Command                        | Description                                                          | Default Shortcut |
+| ------------------------------ | -------------------------------------------------------------------- | ---------------- |
+| `next_comment`                 | Focus the next comment                                               | `j`              |
+| `prev_comment`                 | Focus the previous comment                                           | `k`              |
+| `next_leq_level_comment`       | Focus the next comment with smaller or equal level                   | `l`              |
+| `prev_leq_level_comment`       | Focus the previous comment with smaller or equal level               | `h`              |
+| `next_top_level_comment`       | Focus the next top level comment                                     | `n`              |
+| `prev_top_level_comment`       | Focus the previous top level comment                                 | `p`              |
+| `parent_comment`               | Focus the parent comment (if exists)                                 | `u`              |
+| `toggle_collapse_comment`      | Toggle collapsing the focused comment                                | `tab`            |
+| `up`                           | Scroll up                                                            | `up`             |
+| `down`                         | Scroll down                                                          | `down`           |
+| `page_up`                      | Scroll up half a page                                                | `page_up`        |
+| `page_down`                    | Scroll down half a page                                              | `page_down`      |
+| `open_article_in_browser`      | Open in browser the article associated with the discussed story      | `o`              |
+| `open_article_in_article_view` | Open in article view the article associated with the discussed story | `O`              |
+| `open_story_in_browser`        | Open in browser the discussed story                                  | `s`              |
+| `open_comment_in_browser`      | Open in browser the focused comment                                  | `c`              |
+| `open_link_in_browser`         | Open in browser the {link_id}-th link in the focused comment         | `{link_id} f`    |
+| `open_link_in_article_view`    | Open in article view the {link_id}-th link in the focused comment    | `{link_id} F`    |
 
 #### Search View shortcuts
 
@@ -246,7 +246,8 @@ In `SearchView`, there are two modes: `Navigation` and `Search`. The default mod
 
 ## Configuration
 
-By default, `hackernews-tui` will look for the `hn-tui.toml` user-defined config file inside 
+By default, `hackernews-tui` will look for the `hn-tui.toml` user-defined config file inside
+
 - the [user's config directory](https://docs.rs/dirs-next/latest/dirs_next/fn.config_dir.html)
 - `.config` directory inside the [user's home directory](https://docs.rs/dirs-next/latest/dirs_next/fn.home_dir.html)
 
@@ -262,7 +263,7 @@ For further information about the application's configurations, please refer to
 
 ## Logging
 
-`hackernews-tui` uses `RUST_LOG` environment variable to define the application's [logging level](https://docs.rs/log/0.4.14/log/enum.Level.html) (default to be `INFO`). 
+`hackernews-tui` uses `RUST_LOG` environment variable to define the application's [logging level](https://docs.rs/log/0.4.14/log/enum.Level.html) (default to be `INFO`).
 
 By default, the application creates the `hn-tui.log` log file inside the [user's cache directory](https://docs.rs/dirs-next/latest/dirs_next/fn.cache_dir.html), which can be configured by specifying the `-l` or `--log` option.
 
@@ -287,7 +288,7 @@ By default, the application creates the `hn-tui.log` log file inside the [user's
   - [x] rewrite the theme parser to support more themes and allow to parse themes from known colorschemes
   - [ ] add some extra transition effects
 - improve the keybinding handler
-  - [ ] allow to bind multiple keys to a single command
+  - [x] allow to bind multiple keys to a single command
   - [ ] add prefix key support (emacs-like key chaining - `C-x C-c ...`)
 - [ ] improve the loading progress bar
 - [ ] snipe-like navigation, inspired by [vim-snipe](https://github.com/yangmillstheory/vim-snipe)
diff --git a/config.md b/config.md
index c67d51a..86a0dea 100644
--- a/config.md
+++ b/config.md
@@ -20,13 +20,13 @@ An example config file (with some default config values) can be found in [exampl
 
 ## General
 
-| Option                  | Description                                                                                                           | Default                                                    |
-| ----------------------- | --------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------- |
-| `use_page_scrolling`    | whether to enable page-like scrolling behavior, which automatically adjusts the view based on the scrolling direction | `true`                                                     |
-| `use_pacman_loading`    | whether to use a pacman loading screen or a plain loading screen                                                      | `true`                                                     |
+| Option                  | Description                                                                                                           | Default                                                      |
+| ----------------------- | --------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------ |
+| `use_page_scrolling`    | whether to enable page-like scrolling behavior, which automatically adjusts the view based on the scrolling direction | `true`                                                       |
+| `use_pacman_loading`    | whether to use a pacman loading screen or a plain loading screen                                                      | `true`                                                       |
 | `url_open_command`      | the command the application uses to open an url in browser                                                            | `{ command = 'open', options = [] }`                         |
 | `article_parse_command` | the command the application uses to parse an article into a readable text                                             | `{ command = 'article_md', options = ['--format', 'html'] }` |
-| `client_timeout`        | the timeout (in seconds) when the application's client makes an API request                                           | `32`                                                       |
+| `client_timeout`        | the timeout (in seconds) when the application's client makes an API request                                           | `32`                                                         |
 
 ### Article Parse Command
 
@@ -166,7 +166,7 @@ Specifying the 16-bit color's name will use **the theme palette's color** (as op
 
 ## Keymap
 
-To modify the [default key mapping](https://github.com/aome510/hackernews-TUI#default-shortcuts), simply add new mapping entries to the corresponding keymap section. For example, to change the key shortcuts for the command `next_comment` to `J` and the command `prev_comment` to `K` in the comment view, add these 3 lines to the config file:
+To modify the [default key mapping](https://github.com/aome510/hackernews-TUI#default-shortcuts), simply add new mapping entries to the corresponding keymap section. For example, to change the key shortcut for the command `next_comment` to `J` and the command `prev_comment` to `K` in the comment view, add the below lines to the config file:
 
 ```toml
 [keymap.comment_view_keymap]
@@ -174,6 +174,13 @@ next_comment = "J"
 prev_comment = "K"
 ```
 
+It's possible for a command to have multiple keybindings. For example, to use either `j` or `J` for the `next_comment` command, add the below lines to the config file:
+
+```toml
+[keymap.comment_view_keymap]
+next_comment = ["j", "J"]
+```
+
 ### Custom Keymap
 
 `custom_keymaps` is a config option used to define custom shortcuts to navigate between different story views with stories filtered by certain conditions.
diff --git a/examples/hn-tui.toml b/examples/hn-tui.toml
index c7a608c..f67c997 100644
--- a/examples/hn-tui.toml
+++ b/examples/hn-tui.toml
@@ -62,10 +62,10 @@ launch_hn = { front = "green", effect = "bold" }
 
 [keymap.global_keymap]
 open_help_dialog = "?"
-quit = "C-q"
+quit = ["q", "C-c"]
 close_dialog = "esc"
-goto_previous_view = "C-p"
-goto_search_view = "C-s"
+goto_previous_view = ["backspace", "C-p"]
+goto_search_view = ["/", "C-s"]
 goto_front_page_view = "f1"
 goto_all_stories_view = "f2"
 goto_ask_hn_view = "f3"
@@ -73,10 +73,10 @@ goto_show_hn_view = "f4"
 goto_jobs_view = "f5"
 
 [keymap.edit_keymap]
-move_cursor_left = "left"
-move_cursor_right = "right"
-move_cursor_to_begin = "home"
-move_cursor_to_end = "end"
+move_cursor_left = ["left", "C-b"]
+move_cursor_right = ["right", "C-f"]
+move_cursor_to_begin = ["home", "C-a"]
+move_cursor_to_end = ["end", "C-e"]
 backward_delete_char = "backspace"
 
 [keymap.story_view_keymap]
diff --git a/hackernews_tui/src/config/keybindings.rs b/hackernews_tui/src/config/keybindings.rs
index 5d06650..269487c 100644
--- a/hackernews_tui/src/config/keybindings.rs
+++ b/hackernews_tui/src/config/keybindings.rs
@@ -17,7 +17,7 @@ pub struct KeyMap {
 
 #[derive(Debug, Clone, Deserialize)]
 pub struct CustomKeyMap {
-    pub key: Key,
+    pub key: Keys,
     pub tag: String,
     pub by_date: bool,
     pub numeric_filters: client::StoryNumericFilters,
@@ -27,55 +27,69 @@ config_parser_impl!(CustomKeyMap);
 
 #[derive(Debug, Clone, Deserialize, ConfigParse)]
 pub struct EditKeyMap {
-    pub move_cursor_left: Key,
-    pub move_cursor_right: Key,
-    pub move_cursor_to_begin: Key,
-    pub move_cursor_to_end: Key,
-    pub backward_delete_char: Key,
+    pub move_cursor_left: Keys,
+    pub move_cursor_right: Keys,
+    pub move_cursor_to_begin: Keys,
+    pub move_cursor_to_end: Keys,
+    pub backward_delete_char: Keys,
 }
 
 impl Default for EditKeyMap {
     fn default() -> Self {
         EditKeyMap {
-            move_cursor_left: Key::new(event::Key::Left),
-            move_cursor_right: Key::new(event::Key::Right),
-            move_cursor_to_begin: Key::new(event::Key::Home),
-            move_cursor_to_end: Key::new(event::Key::End),
-            backward_delete_char: Key::new(event::Key::Backspace),
+            move_cursor_left: Keys::new(vec![event::Key::Left.into(), event::Event::CtrlChar('b')]),
+            move_cursor_right: Keys::new(vec![
+                event::Key::Right.into(),
+                event::Event::CtrlChar('f'),
+            ]),
+            move_cursor_to_begin: Keys::new(vec![
+                event::Key::Home.into(),
+                event::Event::CtrlChar('a'),
+            ]),
+            move_cursor_to_end: Keys::new(vec![
+                event::Key::End.into(),
+                event::Event::CtrlChar('e'),
+            ]),
+            backward_delete_char: Keys::new(vec![event::Key::Backspace.into()]),
         }
     }
 }
 
 #[derive(Debug, Clone, Deserialize, ConfigParse)]
 pub struct GlobalKeyMap {
-    pub open_help_dialog: Key,
-    pub quit: Key,
-    pub close_dialog: Key,
+    pub open_help_dialog: Keys,
+    pub quit: Keys,
+    pub close_dialog: Keys,
 
     // view navigation keymaps
-    pub goto_previous_view: Key,
-    pub goto_front_page_view: Key,
-    pub goto_search_view: Key,
-    pub goto_all_stories_view: Key,
-    pub goto_ask_hn_view: Key,
-    pub goto_show_hn_view: Key,
-    pub goto_jobs_view: Key,
+    pub goto_previous_view: Keys,
+    pub goto_front_page_view: Keys,
+    pub goto_search_view: Keys,
+    pub goto_all_stories_view: Keys,
+    pub goto_ask_hn_view: Keys,
+    pub goto_show_hn_view: Keys,
+    pub goto_jobs_view: Keys,
 }
 
 impl Default for GlobalKeyMap {
     fn default() -> Self {
         GlobalKeyMap {
-            open_help_dialog: Key::new('?'),
-            quit: Key::new(event::Event::CtrlChar('q')),
-            close_dialog: Key::new(event::Key::Esc),
-
-            goto_previous_view: Key::new(event::Event::CtrlChar('p')),
-            goto_search_view: Key::new(event::Event::CtrlChar('s')),
-            goto_front_page_view: Key::new(event::Key::F1),
-            goto_all_stories_view: Key::new(event::Key::F2),
-            goto_ask_hn_view: Key::new(event::Key::F3),
-            goto_show_hn_view: Key::new(event::Key::F4),
-            goto_jobs_view: Key::new(event::Key::F5),
+            open_help_dialog: Keys::new(vec!['?'.into()]),
+            quit: Keys::new(vec!['q'.into(), event::Event::CtrlChar('c')]),
+            close_dialog: Keys::new(vec![event::Key::Esc.into()]),
+
+            goto_previous_view: Keys::new(vec![
+                event::Key::Backspace.into(),
+                event::Event::CtrlChar('p'),
+            ]),
+
+            goto_search_view: Keys::new(vec!['/'.into(), event::Event::CtrlChar('s')]),
+
+            goto_front_page_view: Keys::new(vec![event::Key::F1.into()]),
+            goto_all_stories_view: Keys::new(vec![event::Key::F2.into()]),
+            goto_ask_hn_view: Keys::new(vec![event::Key::F3.into()]),
+            goto_show_hn_view: Keys::new(vec![event::Key::F4.into()]),
+            goto_jobs_view: Keys::new(vec![event::Key::F5.into()]),
         }
     }
 }
@@ -83,45 +97,45 @@ impl Default for GlobalKeyMap {
 #[derive(Debug, Clone, Deserialize, ConfigParse)]
 pub struct StoryViewKeyMap {
     // story tags navigation keymaps
-    pub next_story_tag: Key,
-    pub prev_story_tag: Key,
+    pub next_story_tag: Keys,
+    pub prev_story_tag: Keys,
 
     // stories navigation keymaps
-    pub next_story: Key,
-    pub prev_story: Key,
-    pub goto_story: Key,
+    pub next_story: Keys,
+    pub prev_story: Keys,
+    pub goto_story: Keys,
 
     // stories paging/filtering keymaps
-    pub next_page: Key,
-    pub prev_page: Key,
-    pub toggle_sort_by_date: Key,
+    pub next_page: Keys,
+    pub prev_page: Keys,
+    pub toggle_sort_by_date: Keys,
 
     // link opening keymaps
-    pub open_article_in_browser: Key,
-    pub open_article_in_article_view: Key,
-    pub open_story_in_browser: Key,
+    pub open_article_in_browser: Keys,
+    pub open_article_in_article_view: Keys,
+    pub open_story_in_browser: Keys,
 
-    pub goto_story_comment_view: Key,
+    pub goto_story_comment_view: Keys,
 }
 
 impl Default for StoryViewKeyMap {
     fn default() -> Self {
         StoryViewKeyMap {
-            next_story_tag: Key::new('l'),
-            prev_story_tag: Key::new('h'),
-            next_story: Key::new('j'),
-            prev_story: Key::new('k'),
-            goto_story: Key::new('g'),
+            next_story_tag: Keys::new(vec!['l'.into()]),
+            prev_story_tag: Keys::new(vec!['h'.into()]),
+            next_story: Keys::new(vec!['j'.into()]),
+            prev_story: Keys::new(vec!['k'.into()]),
+            goto_story: Keys::new(vec!['g'.into()]),
 
-            next_page: Key::new('n'),
-            prev_page: Key::new('p'),
-            toggle_sort_by_date: Key::new('d'),
+            next_page: Keys::new(vec!['n'.into()]),
+            prev_page: Keys::new(vec!['p'.into()]),
+            toggle_sort_by_date: Keys::new(vec!['d'.into()]),
 
-            open_article_in_browser: Key::new('o'),
-            open_article_in_article_view: Key::new('O'),
-            open_story_in_browser: Key::new('s'),
+            open_article_in_browser: Keys::new(vec!['o'.into()]),
+            open_article_in_article_view: Keys::new(vec!['O'.into()]),
+            open_story_in_browser: Keys::new(vec!['s'.into()]),
 
-            goto_story_comment_view: Key::new(event::Key::Enter),
+            goto_story_comment_view: Keys::new(vec![event::Key::Enter.into()]),
         }
     }
 }
@@ -129,15 +143,15 @@ impl Default for StoryViewKeyMap {
 #[derive(Debug, Clone, Deserialize, ConfigParse)]
 pub struct SearchViewKeyMap {
     // switch mode keymaps
-    pub to_navigation_mode: Key,
-    pub to_search_mode: Key,
+    pub to_navigation_mode: Keys,
+    pub to_search_mode: Keys,
 }
 
 impl Default for SearchViewKeyMap {
     fn default() -> Self {
         SearchViewKeyMap {
-            to_navigation_mode: Key::new(event::Key::Esc),
-            to_search_mode: Key::new('i'),
+            to_navigation_mode: Keys::new(vec![event::Key::Esc.into()]),
+            to_search_mode: Keys::new(vec!['i'.into()]),
         }
     }
 }
@@ -145,186 +159,216 @@ impl Default for SearchViewKeyMap {
 #[derive(Debug, Clone, Deserialize, ConfigParse)]
 pub struct CommentViewKeyMap {
     // comments navigation keymaps
-    pub next_comment: Key,
-    pub prev_comment: Key,
-    pub next_top_level_comment: Key,
-    pub prev_top_level_comment: Key,
-    pub next_leq_level_comment: Key,
-    pub prev_leq_level_comment: Key,
-    pub parent_comment: Key,
+    pub next_comment: Keys,
+    pub prev_comment: Keys,
+    pub next_top_level_comment: Keys,
+    pub prev_top_level_comment: Keys,
+    pub next_leq_level_comment: Keys,
+    pub prev_leq_level_comment: Keys,
+    pub parent_comment: Keys,
 
     // link opening keymaps
-    pub open_comment_in_browser: Key,
-    pub open_link_in_browser: Key,
-    pub open_link_in_article_view: Key,
+    pub open_comment_in_browser: Keys,
+    pub open_link_in_browser: Keys,
+    pub open_link_in_article_view: Keys,
 
     // scrolling
-    pub down: Key,
-    pub up: Key,
-    pub page_down: Key,
-    pub page_up: Key,
+    pub down: Keys,
+    pub up: Keys,
+    pub page_down: Keys,
+    pub page_up: Keys,
 
-    pub toggle_collapse_comment: Key,
+    pub toggle_collapse_comment: Keys,
 }
 
 impl Default for CommentViewKeyMap {
     fn default() -> Self {
         CommentViewKeyMap {
-            next_comment: Key::new('j'),
-            prev_comment: Key::new('k'),
-            next_top_level_comment: Key::new('n'),
-            prev_top_level_comment: Key::new('p'),
-            next_leq_level_comment: Key::new('l'),
-            prev_leq_level_comment: Key::new('h'),
-            parent_comment: Key::new('u'),
-
-            open_comment_in_browser: Key::new('c'),
-            open_link_in_browser: Key::new('f'),
-            open_link_in_article_view: Key::new('F'),
-
-            up: Key::new(event::Key::Up),
-            down: Key::new(event::Key::Down),
-            page_up: Key::new(event::Key::PageUp),
-            page_down: Key::new(event::Key::PageDown),
-
-            toggle_collapse_comment: Key::new(event::Key::Tab),
+            next_comment: Keys::new(vec!['j'.into()]),
+            prev_comment: Keys::new(vec!['k'.into()]),
+            next_top_level_comment: Keys::new(vec!['n'.into()]),
+            prev_top_level_comment: Keys::new(vec!['p'.into()]),
+            next_leq_level_comment: Keys::new(vec!['l'.into()]),
+            prev_leq_level_comment: Keys::new(vec!['h'.into()]),
+            parent_comment: Keys::new(vec!['u'.into()]),
+
+            open_comment_in_browser: Keys::new(vec!['c'.into()]),
+            open_link_in_browser: Keys::new(vec!['f'.into()]),
+            open_link_in_article_view: Keys::new(vec!['F'.into()]),
+
+            up: Keys::new(vec![event::Key::Up.into()]),
+            down: Keys::new(vec![event::Key::Down.into()]),
+            page_up: Keys::new(vec![event::Key::PageUp.into()]),
+            page_down: Keys::new(vec![event::Key::PageDown.into()]),
+
+            toggle_collapse_comment: Keys::new(vec![event::Key::Tab.into()]),
         }
     }
 }
 
 #[derive(Debug, Clone, Deserialize, ConfigParse)]
 pub struct ArticleViewKeyMap {
-    pub down: Key,
-    pub up: Key,
-    pub page_down: Key,
-    pub page_up: Key,
-    pub top: Key,
-    pub bottom: Key,
-
-    pub open_link_dialog: Key,
-    pub link_dialog_focus_next: Key,
-    pub link_dialog_focus_prev: Key,
-
-    pub open_article_in_browser: Key,
-    pub open_link_in_browser: Key,
-    pub open_link_in_article_view: Key,
+    pub down: Keys,
+    pub up: Keys,
+    pub page_down: Keys,
+    pub page_up: Keys,
+    pub top: Keys,
+    pub bottom: Keys,
+
+    pub open_link_dialog: Keys,
+    pub link_dialog_focus_next: Keys,
+    pub link_dialog_focus_prev: Keys,
+
+    pub open_article_in_browser: Keys,
+    pub open_link_in_browser: Keys,
+    pub open_link_in_article_view: Keys,
 }
 
 impl Default for ArticleViewKeyMap {
     fn default() -> Self {
         ArticleViewKeyMap {
-            down: Key::new('j'),
-            up: Key::new('k'),
-            page_down: Key::new('d'),
-            page_up: Key::new('u'),
-            top: Key::new('g'),
-            bottom: Key::new('G'),
-
-            open_link_dialog: Key::new('l'),
-            link_dialog_focus_next: Key::new('j'),
-            link_dialog_focus_prev: Key::new('k'),
-
-            open_article_in_browser: Key::new('o'),
-            open_link_in_browser: Key::new('f'),
-            open_link_in_article_view: Key::new('F'),
+            down: Keys::new(vec!['j'.into()]),
+            up: Keys::new(vec!['k'.into()]),
+            page_down: Keys::new(vec!['d'.into()]),
+            page_up: Keys::new(vec!['u'.into()]),
+            top: Keys::new(vec!['g'.into()]),
+            bottom: Keys::new(vec!['G'.into()]),
+
+            open_link_dialog: Keys::new(vec!['l'.into()]),
+            link_dialog_focus_next: Keys::new(vec!['j'.into()]),
+            link_dialog_focus_prev: Keys::new(vec!['k'.into()]),
+
+            open_article_in_browser: Keys::new(vec!['o'.into()]),
+            open_link_in_browser: Keys::new(vec!['f'.into()]),
+            open_link_in_article_view: Keys::new(vec!['F'.into()]),
         }
     }
 }
 
 #[derive(Debug, Clone)]
-pub struct Key {
-    event: event::Event,
+pub struct Keys {
+    events: Vec<event::Event>,
 }
 
-impl From<Key> for event::EventTrigger {
-    fn from(k: Key) -> Self {
-        k.event.into()
+impl From<Keys> for event::EventTrigger {
+    fn from(k: Keys) -> Self {
+        event::EventTrigger::from_fn(move |e| k.has_event(e))
     }
 }
 
-impl From<Key> for event::Event {
-    fn from(k: Key) -> Self {
-        k.event
-    }
-}
-
-impl std::fmt::Display for Key {
+impl std::fmt::Display for Keys {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self.event {
-            event::Event::Char(c) => write!(f, "{}", c),
-            event::Event::CtrlChar(c) => write!(f, "C-{}", c),
-            event::Event::AltChar(c) => write!(f, "M-{}", c),
-            event::Event::Key(k) => match k {
-                event::Key::Enter => write!(f, "enter"),
-                event::Key::Tab => write!(f, "tab"),
-                event::Key::Backspace => write!(f, "backspace"),
-                event::Key::Esc => write!(f, "esc"),
-
-                event::Key::Left => write!(f, "left"),
-                event::Key::Right => write!(f, "right"),
-                event::Key::Up => write!(f, "up"),
-                event::Key::Down => write!(f, "down"),
-
-                event::Key::Ins => write!(f, "ins"),
-                event::Key::Del => write!(f, "del"),
-                event::Key::Home => write!(f, "home"),
-                event::Key::End => write!(f, "end"),
-                event::Key::PageUp => write!(f, "page_up"),
-                event::Key::PageDown => write!(f, "page_down"),
-
-                event::Key::F1 => write!(f, "f1"),
-                event::Key::F2 => write!(f, "f2"),
-                event::Key::F3 => write!(f, "f3"),
-                event::Key::F4 => write!(f, "f4"),
-                event::Key::F5 => write!(f, "f5"),
-                event::Key::F6 => write!(f, "f6"),
-                event::Key::F7 => write!(f, "f7"),
-                event::Key::F8 => write!(f, "f8"),
-                event::Key::F9 => write!(f, "f9"),
-                event::Key::F10 => write!(f, "f10"),
-                event::Key::F11 => write!(f, "f11"),
-                event::Key::F12 => write!(f, "f12"),
-
-                _ => panic!("unknown key: {:?}", k),
-            },
-            _ => panic!("unknown event: {:?}", self.event),
+        fn fmt_event(e: &event::Event, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+            match e {
+                event::Event::Char(c) => write!(f, "{}", c),
+                event::Event::CtrlChar(c) => write!(f, "C-{}", c),
+                event::Event::AltChar(c) => write!(f, "M-{}", c),
+                event::Event::Key(k) => match k {
+                    event::Key::Enter => write!(f, "enter"),
+                    event::Key::Tab => write!(f, "tab"),
+                    event::Key::Backspace => write!(f, "backspace"),
+                    event::Key::Esc => write!(f, "esc"),
+
+                    event::Key::Left => write!(f, "left"),
+                    event::Key::Right => write!(f, "right"),
+                    event::Key::Up => write!(f, "up"),
+                    event::Key::Down => write!(f, "down"),
+
+                    event::Key::Ins => write!(f, "ins"),
+                    event::Key::Del => write!(f, "del"),
+                    event::Key::Home => write!(f, "home"),
+                    event::Key::End => write!(f, "end"),
+                    event::Key::PageUp => write!(f, "page_up"),
+                    event::Key::PageDown => write!(f, "page_down"),
+
+                    event::Key::F1 => write!(f, "f1"),
+                    event::Key::F2 => write!(f, "f2"),
+                    event::Key::F3 => write!(f, "f3"),
+                    event::Key::F4 => write!(f, "f4"),
+                    event::Key::F5 => write!(f, "f5"),
+                    event::Key::F6 => write!(f, "f6"),
+                    event::Key::F7 => write!(f, "f7"),
+                    event::Key::F8 => write!(f, "f8"),
+                    event::Key::F9 => write!(f, "f9"),
+                    event::Key::F10 => write!(f, "f10"),
+                    event::Key::F11 => write!(f, "f11"),
+                    event::Key::F12 => write!(f, "f12"),
+
+                    _ => panic!("unknown key: {:?}", k),
+                },
+                _ => panic!("unknown event: {:?}", e),
+            }
+        }
+
+        if self.events.is_empty() {
+            return Ok(());
+        }
+
+        if self.events.len() == 1 {
+            fmt_event(&self.events[0], f)
+        } else {
+            write!(f, "[")?;
+            fmt_event(&self.events[0], f)?;
+            for e in &self.events[1..] {
+                write!(f, ", ")?;
+                fmt_event(e, f)?;
+            }
+            write!(f, "]")?;
+            Ok(())
         }
     }
 }
 
-impl Key {
-    pub fn new<T: Into<event::Event>>(e: T) -> Self {
-        Key { event: e.into() }
+impl Keys {
+    pub fn new(events: Vec<event::Event>) -> Self {
+        Keys { events }
+    }
+
+    pub fn has_event(&self, e: &event::Event) -> bool {
+        self.events.iter().any(|x| *x == *e)
     }
 }
 
-config_parser_impl!(Key);
+config_parser_impl!(Keys);
 
-impl<'de> de::Deserialize<'de> for Key {
+impl<'de> de::Deserialize<'de> for Keys {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
         D: Deserializer<'de>,
     {
-        let s = String::deserialize(deserializer)?;
-        let err = Err(de::Error::custom(format!(
-            "failed to parse key: unknown/invalid key {}",
-            s
-        )));
-
-        let chars: Vec<char> = s.chars().collect();
-        let key = {
-            if chars.len() == 1 {
+        #[derive(Deserialize)]
+        #[serde(untagged)]
+        /// an enum representing either
+        /// - a single key string \[1\]
+        /// - an array of multiple key strings
+        ///
+        /// \[1\]: "key string" denotes the string representation of a key
+        enum StringOrVec {
+            String(String),
+            Vec(Vec<String>),
+        }
+
+        /// a helper function that converts a key string into `cursive::event::Event`
+        fn from_key_string_to_event(ks: String) -> Result<event::Event> {
+            let chars: Vec<char> = ks.chars().collect();
+
+            let event = if chars.len() == 1 {
                 // a single character
-                Key::new(chars[0])
+                event::Event::Char(chars[0])
             } else if chars.len() == 3 && chars[1] == '-' {
                 // M-<c> for alt-<c> and C-<c> for ctrl-<c>, with <c> denotes a single character
                 match chars[0] {
-                    'C' => Key::new(event::Event::CtrlChar(chars[2])),
-                    'M' => Key::new(event::Event::AltChar(chars[2])),
-                    _ => return err,
+                    'C' => event::Event::CtrlChar(chars[2]),
+                    'M' => event::Event::AltChar(chars[2]),
+                    _ => {
+                        return Err(anyhow::anyhow!(format!(
+                            "failed to parse key: unknown/invalid key {}",
+                            ks
+                        )))
+                    }
                 }
             } else {
-                let key = match s.as_str() {
+                let key = match ks.as_str() {
                     "enter" => event::Key::Enter,
                     "tab" => event::Key::Tab,
                     "backspace" => event::Key::Backspace,
@@ -355,14 +399,32 @@ impl<'de> de::Deserialize<'de> for Key {
                     "f11" => event::Key::F11,
                     "f12" => event::Key::F12,
 
-                    _ => return err,
+                    _ => {
+                        return Err(anyhow::anyhow!(format!(
+                            "failed to parse key: unknown/invalid key {}",
+                            ks
+                        )))
+                    }
                 };
 
-                Key::new(key)
-            }
+                event::Event::Key(key)
+            };
+
+            Ok(event)
+        }
+
+        let key_strings = match StringOrVec::deserialize(deserializer)? {
+            StringOrVec::String(v) => vec![v],
+            StringOrVec::Vec(v) => v,
         };
 
-        Ok(key)
+        let events = key_strings
+            .into_iter()
+            .map(from_key_string_to_event)
+            .collect::<Result<Vec<_>>>()
+            .map_err(serde::de::Error::custom)?;