Fix rewind selector UI freezing issue

src/core/gpu_thread.cpp

@@ -1478,7 +1478,8 @@ void GPUThread::UpdateRunIdle()
                                      static_cast<u8>(RunIdleReason::SystemPaused) |
                                      static_cast<u8>(RunIdleReason::LoadingScreenActive);
   static constexpr u8 ACTIVATE_MASK =
-    static_cast<u8>(RunIdleReason::FullscreenUIActive) | static_cast<u8>(RunIdleReason::LoadingScreenActive);
+    static_cast<u8>(RunIdleReason::FullscreenUIActive) | static_cast<u8>(RunIdleReason::LoadingScreenActive) |
+    static_cast<u8>(RunIdleReason::RewindSelectorActive);
 
   const bool new_flag = (g_gpu_device && ((s_state.run_idle_reasons & REQUIRE_MASK) != 0) &&
                          ((s_state.run_idle_reasons & ACTIVATE_MASK) != 0));

src/core/gpu_thread.h

@@ -37,6 +37,7 @@ enum class RunIdleReason : u8
   SystemPaused = (1 << 1),
   FullscreenUIActive = (1 << 2),
   LoadingScreenActive = (1 << 3),
+  RewindSelectorActive = (1 << 4),
 };
 
 /// Starts Big Picture UI.

src/core/system.cpp

@@ -5301,6 +5301,9 @@ void System::OpenRewindStateSelector()
   s_state.rewind_selector_states = GetAvailableRewindStates();
   s_state.rewind_selector_index = 0;
 
+  // Set the run idle reason so the GPU thread keeps processing events
+  GPUThread::SetRunIdleReason(GPUThread::RunIdleReason::RewindSelectorActive, true);
+
   // Pause the game
   s_state.was_paused_before_rewind_selector = GPUThread::IsSystemPaused();
   if (!s_state.was_paused_before_rewind_selector)
@@ -5319,6 +5322,9 @@ void System::CloseRewindStateSelector()
   // Unpause if it wasn't paused before
   if (GPUThread::IsSystemPaused() && !s_state.was_paused_before_rewind_selector)
     Host::RunOnCPUThread([]() { System::PauseSystem(false); });
+
+  // Clear the run idle reason
+  GPUThread::SetRunIdleReason(GPUThread::RunIdleReason::RewindSelectorActive, false);
 }
 
 bool System::IsRewindStateSelectorOpen()