Fix Windows cursor with trails disappearing in fullscreen

Fixed by turning off mouse trails when going into fullscreen, then restoring trails when exiting fullscreen or game

platform/windows/os_windows.cpp

@@ -212,6 +212,7 @@ void OS_Windows::initialize_core() {
 	crash_handler.initialize();
 
 	last_button_state = 0;
+	restore_mouse_trails = 0;
 
 	//RedirectIOToConsole();
 	maximized = false;
@@ -1426,6 +1427,13 @@ Error OS_Windows::initialize(const VideoMode &p_desired, int p_video_driver, int
 			video_mode.fullscreen=false;
 		}*/
 		pre_fs_valid = false;
+
+		// If the user has mouse trails enabled in windows, then sometimes the cursor disappears in fullscreen mode.
+		// Save number of trails so we can restore when exiting, then turn off mouse trails
+		SystemParametersInfoA(SPI_GETMOUSETRAILS, 0, &restore_mouse_trails, 0);
+		if (restore_mouse_trails > 1) {
+			SystemParametersInfoA(SPI_SETMOUSETRAILS, 0, 0, 0);
+		}
 	}
 
 	DWORD dwExStyle;
@@ -1770,6 +1778,10 @@ void OS_Windows::finalize() {
 	if (user_proc) {
 		SetWindowLongPtr(hWnd, GWLP_WNDPROC, (LONG_PTR)user_proc);
 	};
+
+	if (restore_mouse_trails > 1) {
+		SystemParametersInfoA(SPI_SETMOUSETRAILS, restore_mouse_trails, 0, 0);
+	}
 }
 
 void OS_Windows::finalize_core() {
@@ -2124,6 +2136,10 @@ void OS_Windows::set_window_fullscreen(bool p_enabled) {
 
 		MoveWindow(hWnd, pos.x, pos.y, size.width, size.height, TRUE);
 
+		SystemParametersInfoA(SPI_GETMOUSETRAILS, 0, &restore_mouse_trails, 0);
+		if (restore_mouse_trails > 1) {
+			SystemParametersInfoA(SPI_SETMOUSETRAILS, 0, 0, 0);
+		}
 	} else {
 		RECT rect;
 
@@ -2143,6 +2159,10 @@ void OS_Windows::set_window_fullscreen(bool p_enabled) {
 		MoveWindow(hWnd, rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top, TRUE);
 
 		pre_fs_valid = true;
+
+		if (restore_mouse_trails > 1) {
+			SystemParametersInfoA(SPI_SETMOUSETRAILS, restore_mouse_trails, 0, 0);
+		}
 	}
 }
 bool OS_Windows::is_window_fullscreen() const {

platform/windows/os_windows.h

@@ -334,6 +334,7 @@ class OS_Windows : public OS {
 	Vector2 im_position;
 
 	MouseMode mouse_mode;
+	int restore_mouse_trails;
 	bool alt_mem;
 	bool gr_mem;
 	bool shift_mem;