QModelIndex and check if a row sibling has focus

[tbscope]

This has the effect, that if the table has the focus my current line is blue in the the front and gray at the end, but I want it blue from the beginning to the end.

Do you mean you want to have the entire row painted with a blue background?

I would probably write a subclassed delegate that takes a pointer to the view (or the selection model) it is set on to avoid the cast.