MessageBox() should have parent window handle

[Vince]

All calls to MessageBox() specify NULL as the parent window. This means after message box display, the user can click into Notepad++ effectively backgrounding the message box without ever closing / acknowledging it. The message boxes should be "modal" - requiring some acknowledgement to close before returning control to Notepad++.

Use Notepad++ handle nppData._nppHandle.

Cheers.