From 440b9ed74903292f5107a28edbe98f44c55f25da Mon Sep 17 00:00:00 2001
From: bicarus <202771338+bicarus-dev@users.noreply.github.com>
Date: Sun, 12 Apr 2026 04:44:46 -0700
Subject: [PATCH] overlay: fix how input is handled when window loses focus
 (#632)

## Link to GitHub Issue or related Pull Request, if one exists
#286

## Description of change
When we migrated to event-based I/O for ImGui, it introduced an issue
where a button would be held down even when the window is not in focus,
because we didn't notify ImGui that the button was released (after the
window lost focus).

Fix the ImGui custom I/O handler so that it immediately releases all
buttons when the window focus is lost.

## Testing
tested on 32-bit windowed mode
---
 src/spice2x/overlay/imgui/impl_spice.cpp | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/src/spice2x/overlay/imgui/impl_spice.cpp b/src/spice2x/overlay/imgui/impl_spice.cpp
index 59eb51c..1f46eb3 100644
--- a/src/spice2x/overlay/imgui/impl_spice.cpp
+++ b/src/spice2x/overlay/imgui/impl_spice.cpp
@@ -349,6 +349,10 @@ void ImGui_ImplSpice_NewFrame() {
     io.DeltaTime = (float) (current_time - g_Time) / g_TicksPerSecond;
     g_Time = current_time;
 
+    // only process new input from devices if window is in focus
+    // (when not in focus, all mouse/keyboard events are treated as released)
+    const auto accept_new_input = superexit::has_focus() && !rawinput::OS_WINDOW_ACTIVE;
+
     // remember old state
     std::array<BYTE, VKEY_MAX> KeysDownOld;
     for (size_t i = 0; i < VKEY_MAX; i++) {
@@ -361,11 +365,6 @@ void ImGui_ImplSpice_NewFrame() {
     g_MouseDown.fill(false);
     g_KeysDown.fill(false);
 
-    // early quit if window not in focus
-    if (!superexit::has_focus() || rawinput::OS_WINDOW_ACTIVE) {
-        return;
-    }
-
     // apply windows mouse buttons
     g_MouseDown[ImGuiMouseButton_Left] |= (get_async_primary_mouse()) != 0;
     g_MouseDown[ImGuiMouseButton_Right] |= (get_async_secondary_mouse()) != 0;
@@ -374,7 +373,7 @@ void ImGui_ImplSpice_NewFrame() {
     // read new keys state
     static long mouse_wheel_last = 0;
     long mouse_wheel = 0;
-    if (RI_MGR != nullptr) {
+    if (RI_MGR != nullptr && accept_new_input) {
         auto devices = RI_MGR->devices_get();
         for (auto &device : devices) {
             switch (device.type) {
@@ -471,7 +470,9 @@ void ImGui_ImplSpice_NewFrame() {
 
     // update OS mouse position
     const auto old_mouse_pos = io.MousePos;
-    ImGui_ImplSpice_UpdateMousePos();
+    if (accept_new_input) {
+        ImGui_ImplSpice_UpdateMousePos();
+    }
     const auto new_mouse_pos = io.MousePos;
 
     // update mouse buttons