KeyTrigger doesn't invoke the command using "ALT" Modifier Key

[salvatorefrancostats]

Describe the bug
Keytriggers with modifier "ALT" doesn't invoke the command

To Reproduce
Steps to reproduce the behavior:

1. Create a WPF Application
2. Create MainWindow
3. Add a keytrigger with Key="Up" and Modifiers="Alt"
4. Add an InvokeCommandAction and bind Command1
5. Add breakpoints on Command1
6. Run the application
7. Press Alt+Up on the keyboard

Current behavior
Command1 won't be fired
Expected behavior
Command1 will be fired

Screenshots

Desktop (please complete the following information):

• Version with bug: 1.1.122

[brianlagunas]

Please create a simple reproduction app.

[salvatorefrancostats]

Hi,
here is a very simple WPF App, using ALT+ArrowDown the command won't be triggered, if you will change it using CTRL as a modifier it will work.

Hope it helps[
WpfApp1.zip
](url)

[brianlagunas]

It appears that WPF is seeing the Alt key as the System key AND the Modifier key, so the Down key is never registered. This should be an easy fix.