Main window(s) stop responding if help about is open

[scrumit]

Minimised window doesn't render if opened when about dialog is open.

Window should render the window, but a blank screen is displayed.

• Platform (Win7, 8, 10? macOS? Linux distro?): Windows 7 Enterprise, Service Pack 1
• Brave Version: 0.11.01
• Steps to reproduce:
  1. Open help, about,
  2. minimise main window
  3. click on taskbar to re-open the main window
• Screenshot if needed:
  What? You want a blank screen?
• Any related issues:
  Possibly all activity on other pages is disabled until the 'about' page is dismissed. I couldn't update this issue when I opened the about page to find out the Brave version number.

[luixxiul]

Even video streaming stops on youtube.

[luixxiul]

The issue was fixed with #5436 (about:brave).