Partially unrevert 05e82c24 for macOS which still needs it

app/streaming/input/input.cpp

@@ -19,6 +19,7 @@ SdlInputHandler::SdlInputHandler(StreamingPreferences& prefs, NvComputer*, int s
       m_StreamHeight(streamHeight),
       m_AbsoluteMouseMode(prefs.absoluteMouseMode),
       m_AbsoluteTouchMode(prefs.absoluteTouchMode),
+      m_PendingFocusGain(false),
       m_LeftButtonReleaseTimer(0),
       m_RightButtonReleaseTimer(0),
       m_DragTimer(0),
@@ -192,6 +193,30 @@ void SdlInputHandler::raiseAllKeys()
     m_KeysDown.clear();
 }
 
+void SdlInputHandler::notifyFocusGained()
+{
+#if defined(Q_OS_DARWIN)
+    int mouseX, mouseY;
+    Uint32 mouseState = SDL_GetGlobalMouseState(&mouseX, &mouseY);
+    if (mouseState & SDL_BUTTON_LMASK) {
+        int x, y, width, height;
+        SDL_GetWindowPosition(m_Window, &x, &y);
+        SDL_GetWindowSize(m_Window, &width, &height);
+        if (mouseX > x && mouseX < x+width && mouseY > y && mouseY < y+height) {
+            if (m_AbsoluteMouseMode) {
+                // Send synthetic mouse motion until the button is lifted
+                m_PendingFocusGain = true;
+            }
+            else {
+                // Recapture the mouse
+                // FIXME: Why is this necessary with SDL_HINT_MOUSE_FOCUS_CLICKTHROUGH?
+                setCaptureActive(true);
+            }
+        }
+    }
+#endif
+}
+
 void SdlInputHandler::notifyFocusLost()
 {
     // Release mouse cursor when another window is activated (e.g. by using ALT+TAB).

app/streaming/input/input.h

@@ -69,6 +69,8 @@ public:
 
     void raiseAllKeys();
 
+    void notifyFocusGained();
+
     void notifyFocusLost();
 
     bool isCaptureActive();
@@ -125,6 +127,8 @@ private:
     bool m_AbsoluteMouseMode;
     bool m_AbsoluteTouchMode;
 
+    bool m_PendingFocusGain;
+
     SDL_TouchFingerEvent m_TouchDownEvent[MAX_FINGERS];
     SDL_TimerID m_LeftButtonReleaseTimer;
     SDL_TimerID m_RightButtonReleaseTimer;

app/streaming/input/mouse.cpp

@@ -122,5 +122,29 @@ Uint32 SdlInputHandler::mouseMoveTimerCallback(Uint32 interval, void *param)
         LiSendMouseMoveEvent(deltaX, deltaY);
     }
 
+    if (me->m_AbsoluteMouseMode && me->m_PendingFocusGain) {
+        int mouseX, mouseY;
+        int windowX, windowY;
+        SDL_Event event;
+        Uint32 buttonState = SDL_GetGlobalMouseState(&mouseX, &mouseY);
+        SDL_GetWindowPosition(me->m_Window, &windowX, &windowY);
+
+        // Send synthetic mouse move events until the button is released
+        event.motion.type = SDL_MOUSEMOTION;
+        event.motion.timestamp = SDL_GetTicks();
+        event.motion.windowID = SDL_GetWindowID(me->m_Window);
+        event.motion.which = 0;
+        event.motion.state = buttonState;
+        event.motion.x = mouseX - windowX;
+        event.motion.y = mouseY - windowY;
+        event.motion.xrel = 0;
+        event.motion.yrel = 0;
+        SDL_PushEvent(&event);
+
+        if ((buttonState & SDL_BUTTON_LMASK) == 0) {
+            me->m_PendingFocusGain = false;
+        }
+    }
+
     return interval;
 }

app/streaming/session.cpp

@@ -1218,7 +1218,10 @@ void Session::exec(int displayOriginX, int displayOriginY)
             break;
 
         case SDL_WINDOWEVENT:
-            if (event.window.event == SDL_WINDOWEVENT_FOCUS_LOST) {
+            if (event.window.event == SDL_WINDOWEVENT_FOCUS_GAINED) {
+                m_InputHandler->notifyFocusGained();
+            }
+            else if (event.window.event == SDL_WINDOWEVENT_FOCUS_LOST) {
                 m_InputHandler->notifyFocusLost();
             }