sdlinput: fix captured mouse coordinates

src/platform/sdl/sdlinput.cpp

@@ -222,6 +222,8 @@ void SdlInputData::Tick(float seconds)
     {
         m_mousecapture = InputDeviceInternal::GetMouseCapture();
         SDL_WM_GrabInput(m_mousecapture ? SDL_GRAB_ON : SDL_GRAB_OFF);
+        mouse = m_app/2;
+        SdlInputData::SetMousePos(mouse);
         //SDL_ShowCursor(m_mousecapture ? SDL_DISABLE : SDL_ENABLE);
     }