windisplay: don't adjust in_window during get_pointer

This restores the old behaviour from before 29a08932ea92bcf0e953994c524cafc1717930b5, which makes in_window true during pointer capture (ie. click-and-drag) even if the cursor leaves the window.

X11 behaviour is already not to adjust in_window.

Fixes #363

panda/src/windisplay/winGraphicsWindow.cxx

@@ -134,15 +134,11 @@ get_pointer(int device) const {
 
     // We recheck this immediately to get the most up-to-date value.
     POINT cpos;
-    if (device == 0 && GetCursorPos(&cpos) && ScreenToClient(_hWnd, &cpos)) {
+    if (device == 0 && result._in_window && GetCursorPos(&cpos) && ScreenToClient(_hWnd, &cpos)) {
       double time = ClockObject::get_global_clock()->get_real_time();
-      RECT view_rect;
-      if (GetClientRect(_hWnd, &view_rect)) {
-        result._in_window = PtInRect(&view_rect, cpos);
-        result._xpos = cpos.x;
-        result._ypos = cpos.y;
-        ((GraphicsWindowInputDevice &)_input_devices[0]).set_pointer(result._in_window, result._xpos, result._ypos, time);
-      }
+      result._xpos = cpos.x;
+      result._ypos = cpos.y;
+      ((GraphicsWindowInputDevice &)_input_devices[0]).set_pointer(result._in_window, result._xpos, result._ypos, time);
     }
   }
   return result;