Fix web content losing focus (#36)
BrowserView was not retaining focus between BrowserWindow blur/focus.
If my understanding is correct, this is an issue in electron itself : https://github.com/electron/electron/issues/28163
This MR is a workaround that forces the focus to the current tab's webContents after changing tabs or when BrowserWindow regains focus (typically after Alt-Tab).
It fixes #36 (closed) as shown in this video: