Do not call setActive(true) when request input panel to show

Observed in kdevelop, that isEnabled() could be false when switching between different tabs with Ctrl+Tab. But Qt may still call show() if you click on the texteditor widget. This leads to isEnabled == false but setActive(true) is called. This causes kdevelop in a usable state because keyboard grab will be created and no key event will reach application because isEnabled == false. Under normal circumstances, key will reach widget first and triggers another text_input_v2 enable to make input method work properly.