RenderThemeWin should match one of Firefox or IE for compatibility sake. IE has a padding that is proportional to the amount of text in the button, which is crazy. So, matching Firefox seems best here. Firefox has a padding:1px 3px on the inner element of buttons. This is in addition to any padding set on the element. So, padding:0 set in the CSS still has that extra few pixels in the actual size of the button, but still returns padding:0 from getComputedStyle.
Created attachment 25799 [details] Sets the padding in RenderThemeWin
Comment on attachment 25799 [details] Sets the padding in RenderThemeWin This looks fine to me, but Hyatt or Adele should offer an opinion before we accept this.
Comment on attachment 25799 [details] Sets the padding in RenderThemeWin I would query the button style for appearance:none, and if it is none, don't apply this internal padding. Once you're not a "Windows" button, I don't think the theme should have any influence any more.
Created attachment 25892 [details] Sets padding only if style->appearance() != NoControlPart
Comment on attachment 25892 [details] Sets padding only if style->appearance() != NoControlPart r=me
http://trac.webkit.org/changeset/39144