From 1f0a21a25e61786ef3e8b3a20908e7631ad29c71 Mon Sep 17 00:00:00 2001
From: Marshall Greenblatt <magreenblatt@gmail.com>
Date: Wed, 9 Nov 2022 13:13:16 -0500
Subject: [PATCH] win: Fix 1px gap with maximized frameless windows on Win11
 (fixes issue #3414)

---
 patch/patch.cfg                  |  3 +++
 patch/patches/views_widget.patch | 17 ++++++++++++++---
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/patch/patch.cfg b/patch/patch.cfg
index c97822fa5..7c57849e7 100644
--- a/patch/patch.cfg
+++ b/patch/patch.cfg
@@ -118,6 +118,9 @@ patches = [
     # Allow override of RWHVBase::GetNewScreenInfosForUpdate() which is now
     # required due to https://crrev.com/96938eb36e in order to use
     # RWHVBase::UpdateScreenInfo() with OSR.
+    #
+    # Windows: Fix 1px gap with maximized frameless windows on Win11.
+    # https://bitbucket.org/chromiumembedded/cef/issues/3414
     'name': 'views_widget',
   },
   {
diff --git a/patch/patches/views_widget.patch b/patch/patches/views_widget.patch
index d419a059c..49d9fe428 100644
--- a/patch/patches/views_widget.patch
+++ b/patch/patches/views_widget.patch
@@ -418,10 +418,21 @@ index d24c447bb8030..29215d6578169 100644
        if (native_widget_delegate->IsDialogBox()) {
          *style |= DS_MODALFRAME;
 diff --git ui/views/win/hwnd_message_handler.cc ui/views/win/hwnd_message_handler.cc
-index db731ec8ab093..f63db294d8480 100644
+index db731ec8ab093..f590ff6d99e85 100644
 --- ui/views/win/hwnd_message_handler.cc
 +++ ui/views/win/hwnd_message_handler.cc
-@@ -826,7 +826,11 @@ bool HWNDMessageHandler::IsVisible() const {
+@@ -625,7 +625,9 @@ void HWNDMessageHandler::SetDwmFrameExtension(DwmFrameState state) {
+   if (!delegate_->HasFrame() && ui::win::IsAeroGlassEnabled() &&
+       !is_translucent_) {
+     MARGINS m = {0, 0, 0, 0};
+-    if (state == DwmFrameState::kOn)
++    // Fix 1px gap with frameless windows on Win11 by not setting DWM margins
++    // when maximized. See CEF issue #3414.
++    if (state == DwmFrameState::kOn && !IsMaximized())
+       m = {0, 0, 1, 0};
+     DwmExtendFrameIntoClientArea(hwnd(), &m);
+   }
+@@ -826,7 +828,11 @@ bool HWNDMessageHandler::IsVisible() const {
  }
  
  bool HWNDMessageHandler::IsActive() const {
@@ -434,7 +445,7 @@ index db731ec8ab093..f63db294d8480 100644
  }
  
  bool HWNDMessageHandler::IsMinimized() const {
-@@ -3224,10 +3228,13 @@ LRESULT HWNDMessageHandler::HandleMouseEventInternal(UINT message,
+@@ -3224,10 +3230,13 @@ LRESULT HWNDMessageHandler::HandleMouseEventInternal(UINT message,
    } else if (event.type() == ui::ET_MOUSEWHEEL) {
      ui::MouseWheelEvent mouse_wheel_event(msg);
      // Reroute the mouse wheel to the window under the pointer if applicable.