From acd61bbed3d14c445fef0dc6245277b10f690481 Mon Sep 17 00:00:00 2001
From: narzoul <narzoul@users.noreply.github.com>
Date: Sat, 23 Jan 2016 23:36:01 +0100
Subject: [PATCH] Disabled DWM transitions and nonclient area rendering

Disabling DWM nonclient area rendering restores proper hit testing for the
non-themed caption buttons.
Transitions are disabled just in case.
---
 DDrawCompat/CompatGdiWinProc.cpp | 19 ++++++++++++++++++-
 DDrawCompat/DDrawCompat.vcxproj  |  4 ++--
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/DDrawCompat/CompatGdiWinProc.cpp b/DDrawCompat/CompatGdiWinProc.cpp
index 025a1df..3edfec8 100644
--- a/DDrawCompat/CompatGdiWinProc.cpp
+++ b/DDrawCompat/CompatGdiWinProc.cpp
@@ -1,5 +1,6 @@
 #define WIN32_LEAN_AND_MEAN
 
+#include <dwmapi.h>
 #include <Windows.h>
 
 #include "CompatGdi.h"
@@ -9,6 +10,7 @@
 
 namespace
 {
+	void disableDwmAttributes(HWND hwnd);
 	void eraseBackground(HWND hwnd, HDC dc);
 	bool isScrollBarVisible(HWND hwnd, LONG windowStyles, LONG sbStyle, LONG sbObjectId);
 	void ncPaint(HWND hwnd);
@@ -19,7 +21,11 @@ namespace
 		if (HC_ACTION == nCode)
 		{
 			auto ret = reinterpret_cast<CWPRETSTRUCT*>(lParam);
-			if (WM_ERASEBKGND == ret->message)
+			if (WM_CREATE == ret->message)
+			{
+				disableDwmAttributes(ret->hwnd);
+			}
+			else if (WM_ERASEBKGND == ret->message)
 			{
 				if (0 != ret->lResult)
 				{
@@ -46,6 +52,17 @@ namespace
 		return CallNextHookEx(nullptr, nCode, wParam, lParam);
 	}
 
+	void disableDwmAttributes(HWND hwnd)
+	{
+		DWMNCRENDERINGPOLICY ncRenderingPolicy = DWMNCRP_DISABLED;
+		DwmSetWindowAttribute(hwnd, DWMWA_NCRENDERING_POLICY,
+			&ncRenderingPolicy, sizeof(ncRenderingPolicy));
+
+		BOOL disableTransitions = TRUE;
+		DwmSetWindowAttribute(hwnd, DWMWA_TRANSITIONS_FORCEDISABLED,
+			&disableTransitions, sizeof(disableTransitions));
+	}
+
 	void drawSizeBox(HWND hwnd, HDC compatDc, const RECT& windowRect, const RECT& clientRect)
 	{
 		LONG style = GetWindowLongPtr(hwnd, GWL_STYLE);
diff --git a/DDrawCompat/DDrawCompat.vcxproj b/DDrawCompat/DDrawCompat.vcxproj
index 6b161bd..fa6ae48 100644
--- a/DDrawCompat/DDrawCompat.vcxproj
+++ b/DDrawCompat/DDrawCompat.vcxproj
@@ -94,7 +94,7 @@
     </ClCompile>
     <Link>
       <ModuleDefinitionFile>DDrawCompat.def</ModuleDefinitionFile>
-      <AdditionalDependencies>dxguid.lib;detours.lib;msimg32.lib;oleacc.lib;uxtheme.lib;%(AdditionalDependencies)</AdditionalDependencies>
+      <AdditionalDependencies>dxguid.lib;detours.lib;msimg32.lib;oleacc.lib;uxtheme.lib;dwmapi.lib;%(AdditionalDependencies)</AdditionalDependencies>
     </Link>
   </ItemDefinitionGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
@@ -121,7 +121,7 @@
     </ClCompile>
     <Link>
       <ModuleDefinitionFile>DDrawCompat.def</ModuleDefinitionFile>
-      <AdditionalDependencies>dxguid.lib;detours.lib;msimg32.lib;oleacc.lib;uxtheme.lib;%(AdditionalDependencies)</AdditionalDependencies>
+      <AdditionalDependencies>dxguid.lib;detours.lib;msimg32.lib;oleacc.lib;uxtheme.lib;dwmapi.lib;%(AdditionalDependencies)</AdditionalDependencies>
       <GenerateDebugInformation>No</GenerateDebugInformation>
     </Link>
   </ItemDefinitionGroup>