Called to retrieve the user interface (UI) state for a window.
The return value is NULL if the focus indicators and the keyboard accelerators are visible. Otherwise, the return value can be one or more of the following values:
UISF_HIDEFOCUS Focus indicators are hidden.
UISF_HIDEACCEL Keyboard accelerators are hidden.
UISF_ACTIVE Windows XP: A control should be drawn in the style used for active controls.
This member function emulates the functionality of the WM_QUERYUISTATE message, as described in the Windows SDK.