diff --git a/extern/imgui_patched/backends/imgui_impl_sdl.cpp b/extern/imgui_patched/backends/imgui_impl_sdl.cpp
index e7ae8d072..00c55ae80 100644
--- a/extern/imgui_patched/backends/imgui_impl_sdl.cpp
+++ b/extern/imgui_patched/backends/imgui_impl_sdl.cpp
@@ -65,6 +65,7 @@
 
 #include "imgui.h"
 #include "imgui_impl_sdl.h"
+#include <stdio.h>
 #include <cmath>
 
 // SDL
@@ -288,6 +289,7 @@ bool ImGui_ImplSDL2_ProcessEvent(const SDL_Event* event)
             if (!platform_io.Monitors.empty() && platform_io.Monitors[0].DpiScale > 1.0f)
             {
                 // The Framebuffer is scaled by an integer ceiling of the actual ratio, so 2.0 not 1.685 on Mac!
+                //printf("multiply by %f\n",platform_io.Monitors[0].DpiScale);
                 mouse_pos.x *= std::ceil(platform_io.Monitors[0].DpiScale);
                 mouse_pos.y *= std::ceil(platform_io.Monitors[0].DpiScale);
             }
@@ -690,10 +692,11 @@ void ImGui_ImplSDL2_NewFrame()
 
     // On Apple and Wayland, The window size is reported in Low DPI, even when running in high DPI mode
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
-    if (!platform_io.Monitors.empty() /*&& platform_io.Monitors[0].DpiScale > 1.0f*/ && display_h != h)
+    if (!platform_io.Monitors.empty() /*&& platform_io.Monitors[0].DpiScale > 1.0f*/ && display_h != h && w != 0)
     {
         io.DisplayFramebufferScale = ImVec2(1.0f, 1.0f);
         io.DisplaySize = ImVec2((float)display_w, (float)display_h);
+        //printf("write %d/%d to DpiScale\n",display_w,w);
         platform_io.Monitors[0].DpiScale=(float)display_w/(float)w;
     }
 
diff --git a/src/gui/debugWindow.cpp b/src/gui/debugWindow.cpp
index 68130d9dc..447ea12d5 100644
--- a/src/gui/debugWindow.cpp
+++ b/src/gui/debugWindow.cpp
@@ -378,6 +378,14 @@ void FurnaceGUI::drawDebug() {
       }
       ImGui::TreePop();
     }
+    if (ImGui::TreeNode("Window Debug")) {
+      ImGui::Text("Screen: %dx%d+%d+%d",scrW,scrH,scrX,scrY);
+      ImGui::Text("Screen (Conf): %dx%d+%d+%d",scrConfW,scrConfH,scrConfX,scrConfY);
+      ImGui::Text("Canvas: %dx%d",canvasW,canvasH);
+      ImGui::Text("Maximized: %d",scrMax);
+      ImGui::Text("System Managed Scale: %d",sysManagedScale);
+      ImGui::TreePop();
+    }
     if (ImGui::TreeNode("Playground")) {
       if (pgSys<0 || pgSys>=e->song.systemLen) pgSys=0;
       if (ImGui::BeginCombo("Chip",fmt::sprintf("%d. %s",pgSys+1,e->getSystemName(e->song.system[pgSys])).c_str())) {
diff --git a/src/gui/gui.cpp b/src/gui/gui.cpp
index 45c4f018b..34baa7778 100644
--- a/src/gui/gui.cpp
+++ b/src/gui/gui.cpp
@@ -1,3 +1,4 @@
+#include <SDL_error.h>
 #define _USE_MATH_DEFINES
 // OK, sorry for inserting the define here but I'm so tired of this extension
 /**
@@ -3074,6 +3075,7 @@ bool FurnaceGUI::loop() {
 
     // update config x/y/w/h values based on scrMax state
     if (updateWindow) {
+      logV("updateWindow is true");
       if (!scrMax) {
         scrConfX=scrX;
         scrConfY=scrY;
@@ -3082,7 +3084,11 @@ bool FurnaceGUI::loop() {
       }
 
       // update canvas size as well
-      SDL_GetRendererOutputSize(sdlRend,&canvasW,&canvasH);
+      if (SDL_GetRendererOutputSize(sdlRend,&canvasW,&canvasH)!=0) {
+        logW("updateWindow: error while getting output size! %s",SDL_GetError());
+      } else {
+        logV("updateWindow: canvas size %dx%d",canvasW,canvasH);
+      }
     }
 
     wantCaptureKeyboard=ImGui::GetIO().WantTextInput;