Well, nice to know it's not just me or that I can't seem to find a way to configure it, maybe I'll file a report with SM although I find it highly unlikely there will be any more SRs for P8.

Thanks jonnybode, the fact remains that the tree panel is not re-sizeable but at least both of your  tips helped minimize the problem, at least now I have access to the refresh icon again. 

Still, would be interesting to see if it works for anyone.