macos: fix window.titleBarStyle on macOS

[vince-fugnitto]

What it does

Fixes: #11583

The commit fixes the handling when setting window.titleBarStyle to custom on macOS (which does not apply) as it has some negative side effects.

How to test

1. start the application on macOS
2. open the preferences-view
3. search for titleBarStyle and change from native to custom
4. the preference change will not take effect

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

Signed-off-by: vince-fugnitto vincent.fugnitto@ericsson.com

[vince-fugnitto]

@msujew I'd like to know your thoughts since I believe you made the initial change.

Should we apply the extra macOS handling at the preference level (and also benefit from not having to do a reload) or change the following line:

theia/packages/core/src/electron-main/electron-main-application.ts

Lines 502 to 503 in d27ebe7

	ipcMain.on(TitleBarStyleChanged, ({ sender }, titleBarStyle: string) => {
	this.useNativeWindowFrame = titleBarStyle === 'native';

to

this.useNativeWindowFrame = isOSX || titleBarStyle === 'native';

[vince-fugnitto]

We should also think of validating preference against included which seems to be ignored at the moment:

theia/packages/core/src/electron-browser/window/electron-window-preferences.ts

Lines 43 to 51 in d27ebe7

	'window.titleBarStyle': {
	type: 'string',
	enum: ['native', 'custom'],
	default: isWindows ? 'custom' : 'native',
	scope: 'application',
	// eslint-disable-next-line max-len
	description: nls.localizeByDefault('Adjust the appearance of the window title bar. On Linux and Windows, this setting also affects the application and context menu appearances. Changes require a full restart to apply.'),
	included: !isOSX
	},

[msujew]

Should we apply the extra macOS handling at the preference level (and also benefit from not having to do a reload) or change the following line:

@vince-fugnitto I believe we should also perform the proposed change in the ElectronMainApplication just to make absolutely sure that the window is never created without a frame. Keeping the current change would be preferable as well.

[vince-fugnitto]

@msujew thank you for the feedback, I made the update and now handle it in both places 👍

[msujew]

I don't have a Mac at hand, but the changes looks reasonable to me 👍

We should probably fix the included preference issue sometime.

[msujew]

@vince-fugnitto The latest change look better to me. I believe that we should be rather safe than sorry in this regard. Checking for isOSX seems perfectly reasonable.