The attached example creates a toplevel widget with a label that has a tool tip.
It gives the toplevel widget a crosshair cursor.
Qt 4: the widget and the label have crosshair cursor. when the tool tip appears, hovering over the tool tip shows arrow cursor, hovering elsewhere over the widget/label shows crosshair
Qt 5.0.2: when moving the mouse in the widget, it keeps the arrow cursor until the mouse moves over the label, which changes the cursor to crosshair, also when then moving to the toplevel widget away from the label. when the tool tip appears, the mouse cursor is changed to arrow. when it vanishes, it stays arrow, and only switches to crosshair again when moving over the label.
Qt 5.1.1 and 5.2: The mouse cursor is an arrow cursor everywhere and whatever is done.