macos: window.titleBarStyle removes top level menu

[vince-fugnitto]

Bug Description:

There is a significant UI/UX bug in macOS regarding the window.titleBarStyle (which should only apply for Linux and Windows) which when set to custom will completely remove the menu and make it difficult to make it return.

native:

custom (missing window controls):

Steps to Reproduce:

1. start the application on macOS
2. open the preferences-view
3. search for titleBarStyle and change from native to custom (accept the prompt)
4. on reload the top level menu will disappear

Note: in order to bring back the menu I had to remove my user preferences, and cached configs:

• rm -rf ~/.theia
• rm -rf ~/Library/ApplicationSupport/Theia\ Electron\ Example/