From b13c14b039aff89ef503dbab30a8148256b6c04f Mon Sep 17 00:00:00 2001
From: ts-korhonen <teemu.s.korhonen@gmail.com>
Date: Wed, 12 Jan 2022 19:39:17 +0200
Subject: [PATCH] Exit full screen mode if changing window

with alt-tab etc. unintended way.
---
 src/win/win_opengl.c | 14 ++++++++++++++
 src/win/win_ui.c     | 10 ++++++++++
 2 files changed, 24 insertions(+)

diff --git a/src/win/win_opengl.c b/src/win/win_opengl.c
index 228cbb56f..99843cd9f 100644
--- a/src/win/win_opengl.c
+++ b/src/win/win_opengl.c
@@ -258,6 +258,13 @@ static int handle_window_messages(UINT message, WPARAM wParam, LPARAM lParam, in
 			free(raw);
 		}
 		return 1;
+	case WM_MOUSELEAVE:
+		if (fullscreen)
+		{
+			/* Leave fullscreen if mouse leaves the renderer window. */
+			PostMessage(GetAncestor(parent, GA_ROOT), WM_LEAVEFULLSCREEN, 0, 0);
+		}
+		return 0;
 	}
 
 	return 0;
@@ -726,7 +733,14 @@ static void opengl_main(void* param)
 				{
 					SetForegroundWindow(window_hwnd);
 					SetFocus(window_hwnd);
+
+					/* Clip cursor to prevent it moving to another monitor. */
+					RECT rect;
+					GetWindowRect(window_hwnd, &rect);
+					ClipCursor(&rect);
 				}
+				else
+					ClipCursor(NULL);
 			}
 
 			if (fullscreen)
diff --git a/src/win/win_ui.c b/src/win/win_ui.c
index 97084858c..c2740f0c7 100644
--- a/src/win/win_ui.c
+++ b/src/win/win_ui.c
@@ -961,6 +961,9 @@ MainWindowProcedure(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
 		break;
 
 	case WM_WINDOWPOSCHANGED:
+		if (video_fullscreen & 1)
+			PostMessage(hwndMain, WM_LEAVEFULLSCREEN, 0, 0);
+
 		pos = (WINDOWPOS*)lParam;
 		GetClientRect(hwndMain, &rect);
 
@@ -1160,6 +1163,13 @@ MainWindowProcedure(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
 		}
 		break;
 
+	case WM_ACTIVATEAPP:
+		/* Leave full screen on switching application except
+		   for OpenGL Core and VNC renderers. */
+		if (video_fullscreen & 1 && wParam == FALSE && vid_api < 3)
+			PostMessage(hwndMain, WM_LEAVEFULLSCREEN, 0, 0);
+		break;
+
 	case WM_ENTERSIZEMOVE:
 		user_resize = 1;
 		break;