[MSGINA][SHELL32] Shutdown/Logoff dialog box overhaul

[arnavbhatt288]

Purpose

Make dialog boxes to gather visual parts from theme and use them along with other fixes.

Also fixes JIRA issue: CORE-17749

Proposed changes

• Convert the dialog boxes back to modal.
• Use WM_TIMER for detecting the press of SHIFT key for shutdown dialog box.
• Lighten the code up a bit.
• Use UXTHEME functions for gathering/using visual parts from theme.

How the customization of dialog boxes works

The dialog boxes now gather and use visual parts from theme specially created for the dialog boxes. Not only the bitmaps (i.e. the dialog box background, flag and buttons) are customizable but also the static texts (the heading and the titles below the buttons) are also customizable. Every customizable control are independent to each other hence you can customize whatever you want for your needs. Those which are supposed to remain "stock" or when a particular visual part can't be loaded for whatever the reason (let's say when classic theme is used or when theme engine is disabled), the dialog boxes default back to its default bitmaps/fonts.

TODO

• [ ] Come up with a tutorial on customization aspect.

Examples