Replace empty window rect checks by a new X11DRV_is_window_rect_mapped
function so that we can reuse that support for off-screen windows.

dlls/x11drv/window.c

diff --git a/dlls/x11drv/window.c b/dlls/x11drv/window.c
index c754c1b..51281c0 100644
--- a/dlls/x11drv/window.c
+++ b/dlls/x11drv/window.c
@@ -151,6 +151,24 @@
 
 
 /***********************************************************************
+ *		X11DRV_is_window_rect_mapped
+ *
+ * Check if the X whole window should be mapped based on its rectangle
+ */
+BOOL X11DRV_is_window_rect_mapped( const RECT *rect )
+{
+    /* don't map if rect is empty */
+    if (IsRectEmpty( rect )) return FALSE;
+
+    /* don't map if rect is off-screen */
+    if (rect->left >= screen_width || rect->top >= screen_height) return FALSE;
+    if (rect->right < 0 || rect->bottom < 0) return FALSE;
+
+    return TRUE;
+}
+
+
+/***********************************************************************
  *              get_window_attributes
  *
  * Fill the window attributes structure for an X window.
@@ -516,7 +534,8 @@
         if (iconic)
             XIconifyWindow( display, data->whole_window, DefaultScreen(display) );
         else
-            if (!IsRectEmpty( &win->rectWindow )) XMapWindow( display, data->whole_window );
+            if (X11DRV_is_window_rect_mapped( &win->rectWindow ))
+                XMapWindow( display, data->whole_window );
     }
 
     XFree(wm_hints);

dlls/x11drv/winpos.c

diff --git a/dlls/x11drv/winpos.c b/dlls/x11drv/winpos.c
index dd97694..3665880 100644
--- a/dlls/x11drv/winpos.c
+++ b/dlls/x11drv/winpos.c
@@ -817,7 +817,8 @@
     {
         if (win->dwStyle & WS_VISIBLE) goto done;
         WIN_SetStyle( hwnd, win->dwStyle | WS_VISIBLE );
-        if (!IsRectEmpty( &win->rectWindow ) && get_whole_window(win) && is_window_top_level(win))
+        if (X11DRV_is_window_rect_mapped( &win->rectWindow ) &&
+            get_whole_window(win) && is_window_top_level(win))
         {
             Display *display = thread_display();
             X11DRV_sync_window_style( display, win );
@@ -832,7 +833,8 @@
     {
         if (!(win->dwStyle & WS_VISIBLE)) goto done;
         WIN_SetStyle( hwnd, win->dwStyle & ~WS_VISIBLE );
-        if (!IsRectEmpty( &win->rectWindow ) && get_whole_window(win) && is_window_top_level(win))
+        if (X11DRV_is_window_rect_mapped( &win->rectWindow ) &&
+            get_whole_window(win) && is_window_top_level(win))
         {
             TRACE( "unmapping win %p\n", hwnd );
             wine_tsx11_lock();
@@ -864,7 +866,7 @@
 
     if (changed & WS_VISIBLE)
     {
-        if (!IsRectEmpty( &wndPtr->rectWindow ))
+        if (X11DRV_is_window_rect_mapped( &wndPtr->rectWindow ))
         {
             if (wndPtr->dwStyle & WS_VISIBLE)
             {
@@ -1013,10 +1015,11 @@
             set_visible_style( winpos->hwnd, FALSE );
         }
         else if ((wndPtr->dwStyle & WS_VISIBLE) &&
-                 !IsRectEmpty( &oldWindowRect ) && IsRectEmpty( &newWindowRect ))
+                 X11DRV_is_window_rect_mapped( &oldWindowRect ) &&
+                 !X11DRV_is_window_rect_mapped( &newWindowRect ))
         {
-            /* resizing to zero size -> unmap */
-            TRACE( "unmapping zero size win %p\n", winpos->hwnd );
+            /* resizing to zero size or off screen -> unmap */
+            TRACE( "unmapping zero size or off-screen win %p\n", winpos->hwnd );
             wine_tsx11_lock();
             XUnmapWindow( display, get_whole_window(wndPtr) );
             wine_tsx11_unlock();
@@ -1044,10 +1047,11 @@
             set_visible_style( winpos->hwnd, TRUE );
         }
         else if ((wndPtr->dwStyle & WS_VISIBLE) &&
-                 IsRectEmpty( &oldWindowRect ) && !IsRectEmpty( &newWindowRect ))
+                 !X11DRV_is_window_rect_mapped( &oldWindowRect ) &&
+                 X11DRV_is_window_rect_mapped( &newWindowRect ))
         {
             /* resizing from zero size to non-zero -> map */
-            TRACE( "mapping non zero size win %p\n", winpos->hwnd );
+            TRACE( "mapping non zero size or off-screen win %p\n", winpos->hwnd );
             XMapWindow( display, get_whole_window(wndPtr) );
         }
         XFlush( display );  /* FIXME: should not be necessary */
@@ -1449,7 +1453,8 @@
 
     if (!(win = WIN_GetPtr( hwnd ))) return;
 
-    if ((win->dwStyle & WS_VISIBLE) && (win->dwExStyle & WS_EX_MANAGED))
+    if ((win->dwStyle & WS_VISIBLE) && (win->dwExStyle & WS_EX_MANAGED) &&
+        X11DRV_is_window_rect_mapped( &win->rectWindow ))
     {
         if (win->dwStyle & WS_MAXIMIZE)
             win->flags |= WIN_RESTORE_MAX;

dlls/x11drv/x11drv.h

diff --git a/dlls/x11drv/x11drv.h b/dlls/x11drv/x11drv.h
index cc40b4a..fcc26c3 100644
--- a/dlls/x11drv/x11drv.h
+++ b/dlls/x11drv/x11drv.h
@@ -517,6 +517,7 @@
 
 extern Window X11DRV_get_client_window( HWND hwnd );
 extern Window X11DRV_get_whole_window( HWND hwnd );
+extern BOOL X11DRV_is_window_rect_mapped( const RECT *rect );
 extern XIC X11DRV_get_ic( HWND hwnd );
 
 inline static Window get_client_window( WND *wnd )