Windows: Alt-Tabbing into Qt widget application, mouse cursor doesn't change to widget custom cursor until mouse is moved

Steps to reproduce:

1) Run any application with a non-toplevel widget that has custom cursor, such as QLineEdit.
2) Move cursor over QLineEdit
3) Alt-Tab out of the application and back into it without moving the cursor.
--> Mouse cursor is the default arrow (or whatever cursor the toplevel widget has been assigned) instead of the custom cursor of line edit. The cursor will change to correct one after the mouse is moved.

This is a regression from 4.8.