/wine/dlls/winex11.drv/x11drv.h
に次のような構造体があり、この whole_window というのが大事らしい：
/* x11drv private window data */
struct x11drv_win_data {
Display *display; /* display connection for the thread owning the window */
XVisualInfo vis; /* X visual used by this window */
Colormap colormap; /* colormap if non-default visual */
HWND hwnd; /* hwnd that this private data belongs to */
Window whole_window; /* X window for the complete window */
Window client_window; /* X window for the client area */
RECT window_rect; /* USER window rectangle relative to parent */
RECT whole_rect; /* X window rectangle for the whole window relative to parent */
RECT client_rect; /* client area relative to parent */
XIC xic; /* X input context */
BOOL managed : 1; /* is window managed? */
BOOL mapped : 1; /* is window mapped? (in either normal or iconic state) */
BOOL iconic : 1; /* is window in iconic state? */
BOOL embedded : 1; /* is window an XEMBED client? */
BOOL shaped : 1; /* is window using a custom region shape? */
BOOL layered : 1; /* is window layered and with valid attributes? */
BOOL use_alpha : 1; /* does window use an alpha channel? */
int wm_state; /* current value of the WM_STATE property */
DWORD net_wm_state; /* bit mask of active x11drv_net_wm_state values */
Window embedder; /* window id of embedder */
unsigned long configure_serial; /* serial number of last configure request */
struct window_surface *surface;
Pixmap icon_pixmap;
Pixmap icon_mask;
unsigned long *icon_bits;
unsigned int icon_size;
};