Hi Konstantina -
I apply a DataTemplate as HeaderTemplate, which works fine with the defaults...
However, if I apply a Theme with the theme manager (either to the RadWindow or application-wide) a few things stop working...
1. The controls in the header template become unresponsive. This can be solved by setting 'obsolete' IsHeaderHitTestVisible
to true (which I found by trial and error and googling, which led to this thread...)
2. (Unrelated to IsHeaderHitTestVisible, but maybe similar cause...)
The stretch of the Header template breaks. In defaults I can place a grid as the template and it stretches all the way from the left start of the header to just left of the standard window controls. Once a Theme is being applied, the header template does not stretch any longer regardless of any setting. I have a workaround now that intercepts resize events on the window and forcibly sets the header width to window width-100, but it feels like a hack.
Ideally I would like things to behave identically with or without a Telerik theme applied with StyleManager :-)
Thanks and Best!
(I should mention that I have another post regarding #2: http://www.telerik.com/community/forums/silverlight/window/theming-vs-headertemplate-issue-on-stretch.aspx