It's an option doing pretty much the same as the highlight of selected
window option. But it is known to conflict especially with some Plasma
themes.
BUG: 310935
FIXED-IN: 4.11
REVIEW: 110140
If the ClientModel does not contain any Clients, which can
happen if there is no desktop window, accessing the data of a
ModelIndex returns an invalid QVariant. Because of that it
needs to be ensured that the QVariant is valid before trying to
cast it to a Client Pointer.
BUG: 304620
FIXED-IN: 4.9.1
REVIEW: 105935