[Qt-creator] small editor suggestion

[Liam Staskawicz]

This is certainly not a major issue, but a very small annoyance I have  
with the QtCreator editor.  There's no indication of where the gutter  
(line numbers and folding glyphs) ends and the actual editing area  
begins.  I find myself always wanting to double check that I don't  
have extra whitespace in my code up against the left edge, since this  
situation makes it a little hard to tell.  If the gutter were colored  
slightly differently, or given some other distinction, I'd be much  
more comfortable!  Thanks, and my apologies if that's not of interest  
to anybody other than me :)

Liam