From 1f85dac530dee933457e99438fd1c82485a2a48e Mon Sep 17 00:00:00 2001
From: Sean Hall <r.sean.hall@gmail.com>
Date: Fri, 4 Jun 2021 13:38:28 -0500
Subject: Fix bug where theme window didn't enlarge client area for default
 DPI.

---
 src/libs/dutil/WixToolset.DUtil/thmutil.cpp | 42 ++++++++++++++++++++++-------
 1 file changed, 33 insertions(+), 9 deletions(-)

diff --git a/src/libs/dutil/WixToolset.DUtil/thmutil.cpp b/src/libs/dutil/WixToolset.DUtil/thmutil.cpp
index a3dce4c2..53257d8e 100644
--- a/src/libs/dutil/WixToolset.DUtil/thmutil.cpp
+++ b/src/libs/dutil/WixToolset.DUtil/thmutil.cpp
@@ -526,6 +526,12 @@ static void ScaleTheme(
     __in BOOL fMenu,
     __in DWORD dwExStyle
     );
+static void AdjustThemeWindowRect(
+    __in THEME* pTheme,
+    __in DWORD dwStyle,
+    __in BOOL fMenu,
+    __in DWORD dwExStyle
+    );
 static void ScaleControls(
     __in THEME* pTheme,
     __in DWORD cControls,
@@ -809,6 +815,7 @@ DAPI_(HRESULT) ThemeCreateParentWindow(
     RECT* pMonitorRect = NULL;
     HMENU hMenu = NULL;
     HWND hWnd = NULL;
+    BOOL fScaledTheme = FALSE;
 
     if (pTheme->hwndParent)
     {
@@ -826,6 +833,7 @@ DAPI_(HRESULT) ThemeCreateParentWindow(
             if (pMonitorContext->nDpi != pTheme->nDpi)
             {
                 ScaleTheme(pTheme, pMonitorContext->nDpi, pMonitorRect->left, pMonitorRect->top, dwStyle, NULL != hMenu, dwExStyle);
+                fScaledTheme = TRUE;
             }
 
             x = pMonitorRect->left + (pMonitorRect->right - pMonitorRect->left - pTheme->nWindowWidth) / 2;
@@ -839,6 +847,12 @@ DAPI_(HRESULT) ThemeCreateParentWindow(
         }
     }
 
+    // Make sure the client area matches the specified width and height.
+    if (!fScaledTheme)
+    {
+        AdjustThemeWindowRect(pTheme, dwStyle, NULL != hMenu, dwExStyle);
+    }
+
     hWnd = ::CreateWindowExW(dwExStyle, szClassName, szWindowName, dwStyle, x, y, pTheme->nWindowWidth, pTheme->nWindowHeight, hwndParent, hMenu, hInstance, lpParam);
     ThmExitOnNullWithLastError(hWnd, hr, "Failed to create theme parent window.");
     ThmExitOnNull(pTheme->hwndParent, hr, E_INVALIDSTATE, "Theme parent window is not set, make sure ThemeDefWindowProc is called for WM_NCCREATE.");
@@ -6597,8 +6611,6 @@ static void ScaleTheme(
     __in DWORD dwExStyle
     )
 {
-    RECT rect = { };
-
     pTheme->nDpi = nDpi;
 
     pTheme->nHeight = DpiuScaleValue(pTheme->nDefaultDpiHeight, pTheme->nDpi);
@@ -6606,13 +6618,7 @@ static void ScaleTheme(
     pTheme->nMinimumHeight = DpiuScaleValue(pTheme->nDefaultDpiMinimumHeight, pTheme->nDpi);
     pTheme->nMinimumWidth = DpiuScaleValue(pTheme->nDefaultDpiMinimumWidth, pTheme->nDpi);
 
-    rect.left = x;
-    rect.top = y;
-    rect.right = x + pTheme->nWidth;
-    rect.bottom = y + pTheme->nHeight;
-    DpiuAdjustWindowRect(&rect, dwStyle, fMenu, dwExStyle, pTheme->nDpi);
-    pTheme->nWindowWidth = rect.right - rect.left;
-    pTheme->nWindowHeight = rect.bottom - rect.top;
+    AdjustThemeWindowRect(pTheme, dwStyle, fMenu, dwExStyle);
 
     ScaleControls(pTheme, pTheme->cControls, pTheme->rgControls, pTheme->nDpi);
 
@@ -6622,6 +6628,24 @@ static void ScaleTheme(
     }
 }
 
+static void AdjustThemeWindowRect(
+    __in THEME* pTheme,
+    __in DWORD dwStyle,
+    __in BOOL fMenu,
+    __in DWORD dwExStyle
+    )
+{
+    RECT rect = { };
+
+    rect.left = 0;
+    rect.top = 0;
+    rect.right = pTheme->nWidth;
+    rect.bottom = pTheme->nHeight;
+    DpiuAdjustWindowRect(&rect, dwStyle, fMenu, dwExStyle, pTheme->nDpi);
+    pTheme->nWindowWidth = rect.right - rect.left;
+    pTheme->nWindowHeight = rect.bottom - rect.top;
+}
+
 static void ScaleControls(
     __in THEME* pTheme,
     __in DWORD cControls,
-- 
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