Prevent closing of entire Xcode window on Command-W when "Quick Open" menu is open

Solution 1:

Here's how you unset the keyboard binding for Close Tab aka ⌘+W.

1. From Settings.app -> Keyboard -> Shortcuts -> App Shortcuts tap the + button
2. From Application dropdown select Xcode
3. Enter Close Tab for the Menu Title
4. set any keyboard shortcut you like

This un-maps ⌘+W shortcut in Xcode app completely. After this you are free to remap the ⌘+W key bindings in Xcode.

In my case I like ⌘+W to close the document so from Xcode -> Preference -> Key Bindings I have these changes (In your case you can bind Ctrl + ⌘+W to Close Tab instead and leave Close Document unmapped).