m5150 / electronmacosclickthrough

An Add On workaround for transparent window click through issues on electron v8 and above

Electron click-through workaround

Overview

This is an addon fix for window click through in transparent regions that was broken in electron 7.0.0beta5 electron/electron#23042 (comment)

By default, a borderless NSWindow will register clicks in opaque regions AND pass clicks through in transparent regions UNLESS you set ignoresMouseEvents at which point all clicks register, regardless of colour, or all clicks pass through.

At some point in electron 7, new BrowserWindow started calling calling the harmless seeming setIgnoreMouseEvents: NO method, which forever disables transparent click through for the new window.

This add-on fixes the problem by patching setIgnoreMouseEvents to be a no-op for ALL NSWindows. It also adds a function MakeWindowIgnoreMouseEvents() which calls the unpatched setIgnoreMouseEvents: YES.

Usage

Call InstallClickThroughPatch() before the new BrowserWindow you want to have the default transparent clickthrough behaviour. Call MakeWindowIgnoreMouseEvents(win.getNativeWindowHandle()) on any BrowserWindow on which you want to all clicks to pass through.

if (process.platform === 'darwin') {
  require('@loomhq/electron-click-through-workaround').InstallClickThroughPatch();
}
...

Future improvements

Hopefully chromium (I guess it's chromium) will stop doing setIgnoreMouseEvents: NO on its windows and this add-on will become obsolete. Failing that, I don't like the indiscriminate way the code disables setIgnoreMouseEvents for all windows, nor the fact that setIgnoreMouseEvents: NO becomes completely unreachable.

Ideally the API would be just this:

DisableSetIgnoreMouseEventsForTheNextWindowToBeCreated() (this "flag-style" API is necessary because by the time we get the BrowserWindow it's too late to apply the patch, the damage has been done). With this implementation you would be free to call BrowserWindow.setIgnoreMouseEvents on other windows for no or full click through.

This cleaner approach would require dynamically subclassing the incoming NSWindow, making setIgnoreMouseEvents a no-op, but I haven't had time to implement and test this.

More info in this SO answer, and take note of the comment in which the surprising tri-state ignoresMouseEvents boolean is explained. https://stackoverflow.com/a/29451199/22147