diff --git a/lcl/interfaces/win32/win32listsl.inc b/lcl/interfaces/win32/win32listsl.inc
index 4970388afb..7d1c229984 100644
--- a/lcl/interfaces/win32/win32listsl.inc
+++ b/lcl/interfaces/win32/win32listsl.inc
@@ -351,9 +351,6 @@ begin
   FFlagSetSelected  := UINT(0);
   FFlagInitStorage  := UINT(CB_INITSTORAGE);
   //Get edit and item sizes
-  Windows.GetClientRect(FWin32List, @R);
-  FEditHeight := R.Bottom;
-  FItemHeight := Windows.SendMessage(FWin32List, CB_GETITEMHEIGHT, 0, 0);
   FDropDownCount := TCustomComboBox(FSender).DropDownCount;
   if FDropDownCount = 0 then
     FDropDownCount := 8;
@@ -375,7 +372,7 @@ begin
     UpdateComboHeight;
     TWin32WSCustomComboBox.SetText(FSender, EditText);
     if EditText = '' then
-     lItemIndex := -1
+      lItemIndex := -1
     else
       lItemIndex := IndexOf(EditText);
     if lItemIndex <> -1 then
@@ -387,11 +384,13 @@ end;
 
 procedure TWin32ComboBoxStringList.SetDropDownCount(const AValue: integer);
 begin
-  FDropDownCount:=AValue;
+  FDropDownCount := AValue;
   UpdateComboHeight;
 end;
 
 function TWin32ComboBoxStringList.GetComboHeight: integer;
+var
+  R: TRect;
 begin
   if (FSender is TCustomComboBox) and (TCustomComboBox(FSender).Style = csSimple) then
   begin
@@ -400,10 +399,11 @@ begin
     Result := FSender.Height;
   end else
   begin
+    Windows.GetClientRect(FWin32List, @R);
     if Count = 0 then
-      Result := FEditHeight + FItemHeight + 2
+      Result := R.Bottom + Windows.SendMessage(FWin32List, CB_GETITEMHEIGHT, 0, 0) + 2
     else
-      Result := FEditHeight + FDropDownCount * FItemHeight + 2;
+      Result := R.Bottom + FDropDownCount * Windows.SendMessage(FWin32List, CB_GETITEMHEIGHT, 0, 0) + 2;
   end;
 end;
 
diff --git a/lcl/interfaces/win32/win32listslh.inc b/lcl/interfaces/win32/win32listslh.inc
index 7d153afd28..6c0779e245 100644
--- a/lcl/interfaces/win32/win32listslh.inc
+++ b/lcl/interfaces/win32/win32listslh.inc
@@ -81,8 +81,6 @@ Type
 
   TWin32ComboBoxStringList = class(TWin32ListStringList)
   private
-    FEditHeight: Integer;
-    FItemHeight: Integer;
     FDropDownCount: Integer;
     procedure SetDropDownCount(const AValue: integer);
   protected
diff --git a/lcl/interfaces/win32/win32wsstdctrls.pp b/lcl/interfaces/win32/win32wsstdctrls.pp
index 68f5be58f5..3c4afa8f3a 100644
--- a/lcl/interfaces/win32/win32wsstdctrls.pp
+++ b/lcl/interfaces/win32/win32wsstdctrls.pp
@@ -74,7 +74,7 @@ type
   private
     class function GetStringList(const ACustomComboBox: TCustomComboBox): TWin32ComboBoxStringList;
   published
-    class function  CreateHandle(const AWinControl: TWinControl;
+    class function CreateHandle(const AWinControl: TWinControl;
           const AParams: TCreateParams): HWND; override;
     class procedure AdaptBounds(const AWinControl: TWinControl;
           var Left, Top, Width, Height: integer; var SuppressMove: boolean); override;
@@ -379,8 +379,7 @@ begin
         if (HWND(WParam) = Info.hwndItem) or (HWND(WParam) = Info.hwndList) then
         begin
           // continue normal processing, don't send to lcl
-          Result := CallDefaultWindowProc(Window, Msg, WParam, LParam);
-          Exit;
+          Exit(CallDefaultWindowProc(Window, Msg, WParam, LParam));
         end;
       end;
     WM_PAINT,
@@ -393,13 +392,18 @@ begin
           LMessage.wParam := WParam;
           LMessage.lParam := LParam;
           LMessage.Result := 0;
-          Result := DeliverMessage(WindowInfo^.WinControl, LMessage);
+          Exit(DeliverMessage(WindowInfo^.WinControl, LMessage));
         end
         else
-          Result := WindowProc(Window, Msg, WParam, LParam);
+          Exit(WindowProc(Window, Msg, WParam, LParam));
       end;
     WM_PRINTCLIENT:
-      Result := CallDefaultWindowProc(Window, Msg, WParam, LParam);
+      Exit(CallDefaultWindowProc(Window, Msg, WParam, LParam));
+    WM_SIZE:
+      begin
+        WindowInfo := GetWin32WindowInfo(Window);
+        WindowInfo^.WinControl.Constraints.UpdateInterfaceConstraints;
+      end;
   end;
   // normal processing
   Result := WindowProc(Window, Msg, WParam, LParam);
@@ -842,10 +846,9 @@ class procedure TWin32WSCustomComboBox.AdaptBounds(const AWinControl: TWinContro
 var
   StringList: TWin32ComboBoxStringList;
 begin
-  if TCustomComboBox(AWinControl).Style=csSimple
-    then exit;
+  if TCustomComboBox(AWinControl).Style = csSimple then Exit;
   StringList := GetStringList(TCustomComboBox(AWinControl));
-  if StringList <> nil then
+  if Assigned(StringList) then
     Height := StringList.ComboHeight;
 end;