[UI] Bugs in UI controls

[valnoxy]

• Cloud: Background of Image list is missing.
• Cloud: After clicking on next, the back button to the image list is disabled.
• Tweaks: Disable AutoInit when user is on WinPE.
• Cloud: Switching to the tab again will occur an error.
• NavBar: Switching pages will create a new thread. (Might be an issue with WPF-UI)