#15 Fixes related to fixes in muimaster.library

[Krzysztof Smiechowicz]

Hi,

I discovered that ZunePaint had a dependency on buggy/non-compatible behavior of Zune and made this patch with fixes. Please let me know if you have any questions.

Buggy Zune behavior:

a) It was blocking all events when an object was not visible (mostly happened when object was on non-visible tab). MUI only blocks if even handler is created with MUI_EHF_GUIMODE flag
b) It was copying string passed via MUIA_Window_Title to internal buffer. MUI is not copying this string, but using string provided by application.