user32: Add the tests for minimize/restore MDI child sequence, fix some failures.

dlls/user32/mdi.c

@@ -1559,8 +1559,8 @@ LRESULT WINAPI DefMDIChildProcW( HWND hwnd, UINT message,
         {
             HWND switchTo = MDI_GetWindow( ci, hwnd, TRUE, WS_MINIMIZE );
 
-            if( switchTo )
-                SendMessageW( switchTo, WM_CHILDACTIVATE, 0, 0 );
+            if (!switchTo) switchTo = hwnd;
+            SendMessageW( switchTo, WM_CHILDACTIVATE, 0, 0 );
 	}
 
         MDI_PostUpdate(client, ci, SB_BOTH+1);

dlls/winex11.drv/winpos.c

@@ -718,6 +718,9 @@ BOOL X11DRV_ShowWindow( HWND hwnd, INT cmd )
     }
     else WIN_ReleasePtr( wndPtr );
 
+    /* if previous state was minimized Windows sets focus to the window */
+    if (style & WS_MINIMIZE) SetFocus( hwnd );
+
     return wasVisible;
 }