SDL: riscos: Ensure the mouse focus is set when creating the window

SDL Commits
#1 
From cb43eb43f81bffaee3d855867b7d432ef3e48391 Mon Sep 17 00:00:00 2001
From: Cameron Cawley <[EMAIL REDACTED]>
Date: Wed, 25 May 2022 21:43:36 +0100
Subject: [PATCH] riscos: Ensure the mouse focus is set when creating the
 window

---
 src/video/riscos/SDL_riscoswindow.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/video/riscos/SDL_riscoswindow.c b/src/video/riscos/SDL_riscoswindow.c
index 05878807be7..f47d33ad7f8 100644
--- a/src/video/riscos/SDL_riscoswindow.c
+++ b/src/video/riscos/SDL_riscoswindow.c
@@ -25,6 +25,8 @@
 #include "SDL_version.h"
 #include "SDL_syswm.h"
 #include "../SDL_sysvideo.h"
+#include "../../events/SDL_mouse_c.h"
+
 
 #include "SDL_riscosvideo.h"
 #include "SDL_riscoswindow.h"
@@ -42,6 +44,8 @@ RISCOS_CreateWindow(_THIS, SDL_Window * window)
 
     window->flags |= SDL_WINDOW_FULLSCREEN;
 
+    SDL_SetMouseFocus(window);
+
     /* All done! */
     window->driverdata = driverdata;
     return 0;