Regaign control of application whe focus is back

Hi, first of all, thanks for your awesome program.

I'm currently using `hackmd-desktop` to take notes of a book in pdf.

So my workflow is to switch to the pdf viewer to change page and come back to hackmd. The issue here is that when the program regains focus it doesn't enter in edit mode or command mode (I'm using the vi layout). I have to click the window with the mouse so I can start using again the vi bindings.

If you use a tiling window manager (such as i3wm) it's a real bummer to have to reach the mouse just for that.

Is there any easy way to fix this?

Thank you!