Vision Client Keystroke Scripts and F2

Sorry to say; No solution because I have similar problems.

We have to rebuilt an old application where navigation can (also) be done by using CTRL+ F1 - 12 and certain functions are triggerd by F2 - F12.
This works fine, as long as no other windows are clicked. When you do, certain CTRL+F keys stop working. (CTRL F5 - F8)
I've got a support request open, but no real answers there. Only to create an unsupported script and attach it to every window to override keystrokes. I.m.h.o. sounds like a work-around.
Post: https://forum.inductiveautomation.com/t/client-keystroke-script/22289/5

I've created a super simple project with just one screen and a button on that screen and keystroke-scripts for CTRL + F1 - F12 and F1 for good meassure.

Keystroke script for CTRL F1 - F12 and F1

def onKeystroke():
	print("keystroke Key: %s, ctrl:%s, alt: %s, shift:%s, action: %s." %('F1', True, False, False, 'Pressed'))

Script on Event Handler of Button in the action-section under actionPerformed

print("Action performed on button: %s, on window: %s." %(event.source.name, system.gui.getParentWindow(event).name))

When the application launches, all CTRL-F keys and F1 are functioning (see log script in the client diagnostics below) When I press the button and the main screen that print statement is executed and visible in the diagnostics as well.
After that, CTRL +F4 and CTRL + F6 are no longer printing their statements. Instead CTRL + F4 seams to close the opened window.... ??

From the client diagnostics (from startup):

Client diagnostics

15:21:41.419 [Thread-0] INFO com.inductiveautomation.ignition.client.gateway_interface.GatewayConnectionManager -- Updated login state. Logged in? true, Username: croon, Roles: [Administrator], Security Zones:
15:21:41.421 [Thread-0] INFO com.inductiveautomation.factorypmi.application.runtime.ClientLaunchHook -- Auto-login successful
15:21:41.481 [ProjectDownloader] INFO Vision.DownloadProjectPane -- Downloading "http://localhost:8088/data/vision/client/project/plainFunctionKeys"...
15:21:41.501 [ProjectDownloader] INFO Vision.DownloadProjectPane -- Connect successful.
15:21:41.502 [ProjectDownloader] INFO Vision.DownloadProjectPane -- Starting download of 7.072 bytes
15:21:41.504 [ProjectDownloader] INFO Vision.DownloadProjectPane -- Download successful
Writing project to cache file C:\Users\croon.ignition\cache\gwlocalhost_8088\C0\CplainFunctionKeys.proj
15:21:42.592 [WebSocket@798491452-39] INFO com.inductiveautomation.ignition.client.gateway_interface.GatewayConnectionManager -- WebSocket session is connected
15:21:42.635 [connection-worker-1] INFO tags.subscriptions -- Changing connected quality to 'Good'
15:21:46.465 [AWT-EventQueue-0] INFO vision.App -- Starting Up...
keystroke Key: F1, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F2, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F3, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F4, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F5, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F6, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F7, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F8, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F9, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F10, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F11, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F12, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F1, ctrl:False, alt: False, shift:False, action: Pressed.
Action performed on button: btnTest, on window: Main.
keystroke Key: F1, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F2, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F3, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F5, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F7, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F8, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F9, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F10, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F11, ctrl:True, alt: False, shift:False, action: Pressed.
keystroke Key: F12, ctrl:True, alt: False, shift:False, action: Pressed.

I'm running this project on 8.1.44 and now imported it on 8.3.4, same results...
Any help/ideas anyone?