TCanvas* C=new TCanvas("a","a")
Now move cursor over the Canvas window, results in error messages of the form:
Error in <TGStatusBar::SetText>: partidx 1 out of range (0,0)
Normally,when the status bar has not been changed, this results in information being displayed in the status bar of the rootbrowser, but it doesn't notice that there is only 1 column and tries to write to the normal four columns hence generating the error message. The status bar of the TCanvas is normally hidden of course. This is annoying because several error messages can easily be generated on the screen resulting in useful information scrolling away.
I found this while developing an Eve based program where I take control of the status bar in the eve browser, to put in my own information, but the problem comes from rootbrowser as shown here.