[Video module]: handle resize from ui
in vlc/include/vlc_vout_window.h
/**
* Reports the current window size.
*
* This function is called by the window implementation and notifies the owner
* of the window what the pixel dimensions of the window are (or should be,
* depending on the windowing system).
*
* \note This function is thread-safe. In case of concurrent call, it is
* undefined which one is taken into account (but at least one is).
*/
static inline void vout_window_ReportSize(vout_window_t *window,
unsigned width, unsigned height)