Add exit button

[JoeZiminski]

This PR closes #545 by adding an 'Exit' button to the main window. I tried to use CTRL+C for copy directly, but forgot that in some cases this still quits the application on Windows. I think under certain conditions the textual event loop is in a strange / awaiting state and the CTRL+C is not caught, defaulting to windows behavior which is to exit the application (also encountered in #458).

As such, CTRL+Q is maintained for copy. However now, CTRL+C does not exit the application, but causes a popup with the following information:

      self.notify(
          "Use CTRL+Q to copy from Inputs and DirectoryTrees.\n"
          "Use ESC or the 'Exit' button to quit the application.\n"
          "CTRL+C can be used to copy after highlighting text with the mouse while pressing 'shift'.",
          timeout=6,
      )

This is because I think it might be annoying if you were trying to copy for the application to exit. It also lets the user know about a cool trick that if you select while holding shift, you can copy any text (found by @cs7-shrey).

[IgorTatarnikov]

Looks great! Is it worth adding a warning when Esc is hit? I worry about incidental key pushes leading to an unexpected exit.

[IgorTatarnikov]

Should this be Esc?

[JoeZiminski]

thanks good catch!

[JoeZiminski]

Good point, do you think CTRL+ESC would be weird? Otherwise a warning pop-up window is definitely dooable, I think I am just being lazy 😅

[IgorTatarnikov]

Ctrl+ESC would work but a pop-up might be nice for the future! Maybe change to Ctrl + Esc for now and open an issue to make a pop-up in the future.

[JoeZiminski]

Hey @IgorTatarnikov in the end I added the warning window, it was pretty quick! If you could take a quick look whenever you have time that would be great. Cheers!

[IgorTatarnikov]

Works great! The confirmation popup is a great addition.