* separated window, app and context menu code
* got rid of all the global variables (which were accessed completely without
locking, and the code with regards to the preference window sill needs
fixing)
* extracted some defines and helper functions to MailSupport.cpp, though I later
saw Utilities.cpp...
* got rid of the FONT_SIZE define which was used in some (but not all) controls
to override the system font size
* worked in Header.cpp to get the controls layout font sensitive with correct
alignment too, some problems remain when resizing the window
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@22122 a95241bf-73f2-0310-859d-f6bbb57e9c96