From 97df73acea61ddf94c135bc37e4f402b6e5a6cab Mon Sep 17 00:00:00 2001
From: goaaats <goatsdev@protonmail.com>
Date: Mon, 8 Dec 2025 21:00:08 +0100
Subject: [PATCH] Ensure that we don't catch mouse up events without
 corresponding mouse down events Fixes an issue wherein the cursor could get
 locked by the game if WantCaptureMouse becomes true in between down and up
 events

---
 .../InputHandler/Win32InputHandler.cs         | 38 ++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/Dalamud/Interface/ImGuiBackend/InputHandler/Win32InputHandler.cs b/Dalamud/Interface/ImGuiBackend/InputHandler/Win32InputHandler.cs
index 0b2e27b57..6b26ce37d 100644
--- a/Dalamud/Interface/ImGuiBackend/InputHandler/Win32InputHandler.cs
+++ b/Dalamud/Interface/ImGuiBackend/InputHandler/Win32InputHandler.cs
@@ -7,6 +7,7 @@ using System.Runtime.InteropServices;
 using System.Text;
 
 using Dalamud.Bindings.ImGui;
+using Dalamud.Console;
 using Dalamud.Memory;
 using Dalamud.Utility;
 
@@ -37,6 +38,8 @@ internal sealed unsafe partial class Win32InputHandler : IImGuiInputHandler
     private readonly WndProcDelegate wndProcDelegate;
     private readonly nint platformNamePtr;
 
+    private readonly IConsoleVariable<bool> cvLogMouseEvents;
+
     private ViewportHandler viewportHandler;
 
     private int mouseButtonsDown;
@@ -87,6 +90,11 @@ internal sealed unsafe partial class Win32InputHandler : IImGuiInputHandler
         this.cursors[(int)ImGuiMouseCursor.ResizeNwse] = LoadCursorW(default, IDC.IDC_SIZENWSE);
         this.cursors[(int)ImGuiMouseCursor.Hand] = LoadCursorW(default, IDC.IDC_HAND);
         this.cursors[(int)ImGuiMouseCursor.NotAllowed] = LoadCursorW(default, IDC.IDC_NO);
+
+        this.cvLogMouseEvents = Service<ConsoleManager>.Get().AddVariable(
+            "imgui.log_mouse_events",
+            "Log mouse events to console for debugging",
+            false);
     }
 
     /// <summary>
@@ -267,11 +275,23 @@ internal sealed unsafe partial class Win32InputHandler : IImGuiInputHandler
             case WM.WM_XBUTTONDOWN:
             case WM.WM_XBUTTONDBLCLK:
             {
+                if (this.cvLogMouseEvents.Value)
+                {
+                    Log.Verbose(
+                        "Handle MouseDown {Btn} WantCaptureMouse: {Want} mouseButtonsDown: {Down}",
+                        GetButton(msg, wParam),
+                        io.WantCaptureMouse,
+                        this.mouseButtonsDown);
+                }
+
                 var button = GetButton(msg, wParam);
                 if (io.WantCaptureMouse)
                 {
                     if (this.mouseButtonsDown == 0 && GetCapture() == nint.Zero)
+                    {
                         SetCapture(hWndCurrent);
+                    }
+
                     this.mouseButtonsDown |= 1 << button;
                     io.AddMouseButtonEvent(button, true);
                     return default(LRESULT);
@@ -288,12 +308,28 @@ internal sealed unsafe partial class Win32InputHandler : IImGuiInputHandler
             case WM.WM_MBUTTONUP:
             case WM.WM_XBUTTONUP:
             {
+                if (this.cvLogMouseEvents.Value)
+                {
+                    Log.Verbose(
+                        "Handle MouseUp   {Btn} WantCaptureMouse: {Want} mouseButtonsDown: {Down}",
+                        GetButton(msg, wParam),
+                        io.WantCaptureMouse,
+                        this.mouseButtonsDown);
+                }
+
                 var button = GetButton(msg, wParam);
-                if (io.WantCaptureMouse)
+
+                // Need to check if we captured the button event away from the game here, otherwise the game might get
+                // a down event but no up event, causing the cursor to get stuck.
+                // Can happen if WantCaptureMouse becomes true in between down and up
+                if (io.WantCaptureMouse && (this.mouseButtonsDown & (1 << button)) != 0)
                 {
                     this.mouseButtonsDown &= ~(1 << button);
                     if (this.mouseButtonsDown == 0 && GetCapture() == hWndCurrent)
+                    {
                         ReleaseCapture();
+                    }
+
                     io.AddMouseButtonEvent(button, false);
                     return default(LRESULT);
                 }