fix: #7216, hide taskbar on chat modal invocation on mobile

public/src/modules/chat.js

@@ -297,6 +297,7 @@ define('chat', [
 
 	module.enableMobileBehaviour = function (modalEl) {
 		app.toggleNavbar(false);
+		taskbar.toggleVisibility(false);
 		modalEl.attr('data-mobile', '1');
 		var messagesEl = modalEl.find('.modal-body');
 		messagesEl.css('height', module.calculateChatListHeight(modalEl));
@@ -308,6 +309,7 @@ define('chat', [
 
 	module.disableMobileBehaviour = function () {
 		app.toggleNavbar(true);
+		taskbar.toggleVisibility(true);
 	};
 
 	module.calculateChatListHeight = function (modalEl) {

public/src/modules/taskbar.js

@@ -182,5 +182,9 @@ define('taskbar', ['benchpress', 'translator'], function (Benchpress, translator
 		taskbar.tasklist.find('[data-module="' + module + '"][data-uuid="' + uuid + '"] [component="taskbar/title"]').text(newTitle);
 	};
 
+	taskbar.toggleVisibility = function (visible) {
+		taskbar.taskbar.toggleClass('hidden', !visible);
+	};
+
 	return taskbar;
 });