Currently, there is no concept of not having a cursor set on
a Window. Qt::ArrowCursor is always set instead. This causes
bugs when native child widgets are involved, for example setting
a cursor on the native widget's parent no longer works since
the child's Qt::ArrowCursor applies.
Introduce QWindowPrivate::hasCursor tracking whether a cursor
has been explicitly set and clear in QWindow::unsetCursor().
Handle 0 in QPlatformCursor::changeCursor() to mean
"unsetCursor()":
- Windows: Introduce default constructor for QWindowsWindowCursor
meaning "0". Search for applicable parent cursor in applyCursor.
- XCB: No big changes required, set XCB_CURSOR_NONE for no cursor.
- Other platforms: Assume Qt::ArrowCursor when cursor = 0 is
passed for now.
Task-number: QTBUG-28879
Change-Id: Id82722592f3cd5fe577a5b64dcc600c85cfea484
Reviewed-by: Jonathan Liu <net147@gmail.com>
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>
c24a7377dd