Hotkey control

[thoemmi]

This PR adds a HotKeyBox to MahApps.Metro with following features:

• handles all hotkeys except Tab, Shift+Tab (used for navigation) and Back (clears the hotkey)
• optionally modifier keys (Ctrl, Alt, Shift, or Win) are required
• supports watermark
• validation works
• templating support
• uses Win API GetKeyNameText to get a textual representation of the keys. No localization is required, as it only depends on the keyboard layout as configured in Windows. (I have a German keyboard, therefore you see STRG+UMSCHALT+POS1 in the screenshot; with an English layout it would say CTRL+SHIFT+HOME)
• supports ControlsHelper.ContentCharacterCasing. The reason was that Windows is not consistent about what GetKeyNameText returns. E.g. on my machine with an English keyboard layout it returns normal-cased modifier keys, but upper-case function keys, which results in Ctrl+Shift+HOME. You may attach Controls:ControlsHelper.ContentCharacterCasing="Upper" to get consistent output.

The only purpose of HotKeyBox is to enable the user to enter a hotkey. Registering and handling hotkeys is out of its scope. I have added the control to the sample app and use NHotkey (NuGet) for the handling.

[bigworld12]

exactly what I have been looking for, thanks!

[punker76]

@thoemmi 👍

[moser96]

Create work 👍 .
I just included it in my project and it's working as expected ;)

[thoemmi]

Thanks for your feedback, @moser96. Glad to hear that 😄