diff --git a/widget/gtk/nsWindow.cpp b/widget/gtk/nsWindow.cpp
--- a/widget/gtk/nsWindow.cpp
+++ b/widget/gtk/nsWindow.cpp
@@ -3787,11 +3787,12 @@
     mPendingConfigures--;
   }
 
   // Don't fire configure event for scale changes, we handle that
   // OnScaleChanged event. Skip that for toplevel windows only.
-  if (mWindowType == eWindowType_toplevel) {
+  if (mWindowType == eWindowType_toplevel ||
+      mWindowType == eWindowType_dialog) {
     MOZ_DIAGNOSTIC_ASSERT(mGdkWindow,
                           "Getting configure for invisible window?");
     if (mWindowScaleFactor != gdk_window_get_scale_factor(mGdkWindow)) {
       LOG("  scale factor changed to %d,return early",
           gdk_window_get_scale_factor(mGdkWindow));
@@ -4864,10 +4865,11 @@
   // Force scale factor recalculation
   if (!mGdkWindow) {
     mWindowScaleFactorChanged = true;
     return;
   }
+  LOG("OnScaleChanged -> %d\n", gdk_window_get_scale_factor(mGdkWindow));
 
   // Gtk supply us sometimes with doubled events so stay calm in such case.
   if (gdk_window_get_scale_factor(mGdkWindow) == mWindowScaleFactor) {
     return;
   }