Calc's tab colors and GTK tabs

[Kohei Yoshida]

Hi there,

I just noticed that, on master, tabs are rendered natively when using 
GTK backend, which is nice, and I like it a lot.

Unfortunately this broke Calc's tab color feature.  Now, I'm not too 
familiar with GTK's tab implementation to see if GTK supports changing 
tab colors natively.  Does anybody who is more familiar with GTK have 
any idea about this?  I hope this can be fixed rather trivially.

Thanks,

Kohei

-- 
Kohei Yoshida, LibreOffice hacker, Calc