Interacting with another app when window.SetFullScreen(true) will cause the application to hide itself.

[bartimusprimed]

I was asked to open a report for this from the slack channel.

Describe the bug:

When setting window.SetFullScreen(true), the window will hide itself when focusing another window.

To Reproduce:

1. Set up normal application.
2. Set window.SetFullScreen(true)
3. Click any other application on the taskbar or on another monitor.
4. The fyne app will hide and needs to be alt+tabbed or clicked on to be shown again.

Device (please complete the following information):

• OS: Windows
• Version: 10 (current)
• Go version: 1.17
• Fyne version: v2.0.4

[andydotxyz]

Fixed on develop ready for testing and v2.1