MainPane: leave more space to chat in small window

TODO.md

@@ -91,6 +91,8 @@
 - Way to open context menus without a right mouse button
 - `smartVerticalFlick()` gradual acceleration
 - Make banner buttons look better
+- When window is reduced enough for main pane to be invisible, transition
+  between pane and page with alt+S is laggy when the page is a chat
 
 - Choose a better default easing type for animations
 - Make HListView scrollbars visible

src/gui/UI.qml

@@ -70,7 +70,7 @@ Item {
 
     MainPane {
         id: mainPane
-        maximumSize: parent.width - theme.minimumSupportedWidth
+        maximumSize: parent.width - theme.minimumSupportedWidth * 1.5
     }
 
     PageLoader {