Some adaptions to better align with Office 2013

[chrfin]

• positioning of the text in the screen tip when no image/icon is set
• background of the split button on hover

[batzen]

Thanks for contributing.
I will implement the fixes on my own for version 4.0.
The reasons for that are:

• The colors should be fixed for all buttons as there are no hover borders at all in Office 2013 (didn't ever notice that till you brought this up)
• The trigger for the icon should be part of ControlTemplate.Triggers (to be consistent with the other triggers)
• The indentation for your trigger is a bit off

So instead of forcing you to edit your PR I will take your ideas/changes and add them to the code.

Are you ok with that way?

[chrfin]

Are you ok with that way?

Sure, go ahead and take whatever you can use...