4 files changed, 28 insertions, 15 deletions
diff --git a/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.H b/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.H
index e81120fea..6dbfa7848 100644
--- a/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.H
+++ b/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.H
@@ -37,14 +37,14 @@ protected:
   RECT screens[MAX_SCREENS];
   RECT work_area[MAX_SCREENS];
   float dpi[MAX_SCREENS][2];
+  float scale_of_screen[MAX_SCREENS];
 
   static BOOL CALLBACK screen_cb(HMONITOR mon, HDC, LPRECT r, LPARAM);
   BOOL screen_cb(HMONITOR mon, HDC, LPRECT r);
-  int screen_num_unscaled(int x, int y);
   int get_mouse_unscaled(int &mx, int &my);
 
 public:
-  Fl_WinAPI_Screen_Driver() : Fl_Screen_Driver() { scale_ = 1; }
+  Fl_WinAPI_Screen_Driver() : Fl_Screen_Driver() { }
   // --- display management
   virtual int visual(int flags);
   // --- screen configuration
@@ -55,6 +55,7 @@ public:
   virtual int h();
   virtual void screen_xywh(int &X, int &Y, int &W, int &H, int n);
   virtual void screen_dpi(float &h, float &v, int n=0);
+  int screen_num_unscaled(int x, int y);
   float DWM_scaling_factor(int screen_num);
   virtual void screen_work_area(int &X, int &Y, int &W, int &H, int n);
   // --- audible output
@@ -87,11 +88,9 @@ public:
     return SYSTEMWIDE_APP_SCALING;
   }
 #endif
-  virtual float scale(int n) {return scale_;}
-  virtual void scale(int n, float f) { scale_ = f;}
+  virtual float scale(int n) {return scale_of_screen[n];}
+  virtual void scale(int n, float f) { scale_of_screen[n] = f;}
   virtual float desktop_scale_factor();
-private:
-  float scale_;
 };
 
 
diff --git a/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx b/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx
index e4a3361f5..236a33288 100644
--- a/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx
+++ b/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx
@@ -100,6 +100,7 @@ BOOL Fl_WinAPI_Screen_Driver::screen_cb(HMONITOR mon, HDC, LPRECT r)
     screens[num_screens] = mi.rcMonitor;
     // If we also want to record the work area, we would also store mi.rcWork at this point
     work_area[num_screens] = mi.rcWork;
+    scale_of_screen[num_screens] = 1;
     /*fl_alert("screen %d %d,%d,%d,%d work %d,%d,%d,%d",num_screens,
     screens[num_screens].left,screens[num_screens].right,screens[num_screens].top,screens[num_screens].bottom,
     work_area[num_screens].left,work_area[num_screens].right,work_area[num_screens].top,work_area[num_screens].bottom);
@@ -152,6 +153,7 @@ void Fl_WinAPI_Screen_Driver::init()
   screens[0].right = GetSystemMetrics(SM_CXSCREEN);
   screens[0].bottom = GetSystemMetrics(SM_CYSCREEN);
   work_area[0] = screens[0];
+  scale_of_screen[0] = 1;
 }
 
 
@@ -159,10 +161,10 @@ void Fl_WinAPI_Screen_Driver::screen_work_area(int &X, int &Y, int &W, int &H, i
 {
   if (num_screens < 0) init();
   if (n < 0 || n >= num_screens) n = 0;
-  X = work_area[n].left/scale_;
-  Y = work_area[n].top/scale_;
-  W = (work_area[n].right - X)/scale_;
-  H = (work_area[n].bottom - Y)/scale_;
+  X = work_area[n].left/scale_of_screen[n];
+  Y = work_area[n].top/scale_of_screen[n];
+  W = (work_area[n].right - X)/scale_of_screen[n];
+  H = (work_area[n].bottom - Y)/scale_of_screen[n];
 }
 
 
@@ -174,10 +176,10 @@ void Fl_WinAPI_Screen_Driver::screen_xywh(int &X, int &Y, int &W, int &H, int n)
     n = 0;
 
   if (num_screens > 0) {
-    X = screens[n].left/scale_;
-    Y = screens[n].top/scale_;
-    W = (screens[n].right - screens[n].left)/scale_;
-    H = (screens[n].bottom - screens[n].top)/scale_;
+    X = screens[n].left/scale_of_screen[n];
+    Y = screens[n].top/scale_of_screen[n];
+    W = (screens[n].right - screens[n].left)/scale_of_screen[n];
+    H = (screens[n].bottom - screens[n].top)/scale_of_screen[n];
   } else {
     /* Fallback if something is broken... */
     X = 0;
diff --git a/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.H b/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.H
index 61d456edb..7f548c58b 100644
--- a/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.H
+++ b/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.H
@@ -61,6 +61,7 @@ class FL_EXPORT Fl_WinAPI_Window_Driver : public Fl_Window_Driver
     HICON big_icon;
     HICON small_icon;
   };
+  int screen_num_;
 private:
   void shape_bitmap_(Fl_Image* b);
   void shape_alpha_(Fl_Image* img, int offset);
@@ -70,6 +71,8 @@ public:
   static inline Fl_WinAPI_Window_Driver* driver(Fl_Window *w) {return (Fl_WinAPI_Window_Driver*)w->driver();}
   HDC private_dc; // used for OpenGL
   RECT border_width_title_bar_height(int &bx, int &by, int &bt);
+  virtual void screen_num(int n) { screen_num_ = n; }
+  virtual int screen_num();
 
   struct icon_data *icon_;
   HCURSOR cursor;
diff --git a/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.cxx b/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.cxx
index 0229f3cce..079ca743d 100644
--- a/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.cxx
+++ b/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.cxx
@@ -48,6 +48,7 @@ Fl_WinAPI_Window_Driver::Fl_WinAPI_Window_Driver(Fl_Window *win)
   icon_ = new icon_data;
   memset(icon_, 0, sizeof(icon_data));
   cursor = NULL;
+  screen_num_ = -1;
 }
 
 
@@ -60,6 +61,13 @@ Fl_WinAPI_Window_Driver::~Fl_WinAPI_Window_Driver()
   delete icon_;
 }
 
+int Fl_WinAPI_Window_Driver::screen_num() {
+  if (pWindow->parent()) {
+    screen_num_ = pWindow->top_window()->driver()->screen_num();
+  }
+  return screen_num_ >= 0 ? screen_num_ : 0;
+}
+
 
 RECT // frame of the decorated window in screen coordinates
   Fl_WinAPI_Window_Driver::border_width_title_bar_height(
@@ -395,7 +403,7 @@ void Fl_WinAPI_Window_Driver::make_current() {
 #endif // USE_COLORMAP
   
   fl_graphics_driver->clip_region(0);
-  fl_graphics_driver->scale(Fl::screen_driver()->scale(0));
+  fl_graphics_driver->scale(Fl::screen_driver()->scale(screen_num()));
   fl_graphics_driver->line_style(FL_SOLID); // scale also default line width
 }
 
@@ -489,6 +497,7 @@ void Fl_WinAPI_Window_Driver::hide() {
   if (pWindow->non_modal() && Fl::first_window() && Fl::first_window()->shown())
     Fl::first_window()->show();
   delete ip;
+  screen_num_ = -1;
 }