Fix issue #96 : Seek dialog improvements
OK button renamed to Seek - no longer closes dialog when pressed
Can now edit position controls and press return to do seek then continue editing position
Tab order fixed and accelerators added
Duration/Position/FPS readout controls are now read-only edit controls to allow copying and pasting from them.

git-svn-id: http://graph-studio-next.googlecode.com/svn/trunk@97 c2f33eb2-41b2-391d-4cb4-d9d0608729ba