hotkeys: Add collapse/show message hotkey.

Fixes #4540

frontend_tests/node_tests/hotkey.js

@@ -225,7 +225,7 @@ function stubbing(func_name_to_stub, test_function) {
 
     // Check that they do nothing while in the settings overlay
     overlays.settings_open = return_true;
-    assert_unmapped('@*+rRjJkKsSuvi:GM');
+    assert_unmapped('@*+-rRjJkKsSuvi:GM');
     overlays.settings_open = return_false;
 
     // TODO: Similar check for being in the subs page
@@ -233,6 +233,7 @@ function stubbing(func_name_to_stub, test_function) {
     assert_mapping('@', 'compose_actions.reply_with_mention');
     assert_mapping('*', 'message_flags.toggle_starred');
     assert_mapping('+', 'reactions.toggle_emoji_reaction');
+    assert_mapping('-', 'condense.toggle_collapse');
     assert_mapping('r', 'compose_actions.respond_to_message');
     assert_mapping('R', 'compose_actions.respond_to_message', true);
     assert_mapping('j', 'navigate.down');

static/js/condense.js

@@ -79,6 +79,19 @@ exports.collapse = function (row) {
     process_row(row);
     process_row(home_row);
 };
+
+exports.toggle_collapse = function (message) {
+    var row = current_msg_list.get_row(message.id);
+    if (!row) {
+        return;
+    }
+    if (message.collapsed) {
+        condense.uncollapse(row);
+    } else {
+        condense.collapse(row);
+    }
+};
+
 exports.clear_message_content_height_cache = function () {
     _message_content_height_cache = new Dict();
 };

static/js/hotkey.js

@@ -81,6 +81,7 @@ var keydown_either_mappings = {
 var keypress_mappings = {
     42: {name: 'star_message', message_view_only: true}, // '*'
     43: {name: 'thumbs_up_emoji', message_view_only: true}, // '+'
+    45: {name: 'toggle_message_collapse', message_view_only: true}, // '-'
     47: {name: 'search', message_view_only: false}, // '/'
     58: {name: 'open_reactions', message_view_only: true}, // ':'
     63: {name: 'show_shortcuts', message_view_only: false}, // '?'
@@ -665,6 +666,9 @@ exports.process_hotkey = function (e, hotkey) {
         case 'toggle_mute':
             muting_ui.toggle_mute(msg);
             return true;
+        case 'toggle_message_collapse':
+            condense.toggle_collapse(msg);
+            return true;
     }
 
     return false;