Add set_focused function callback to window

ui/drivers/null/ui_null_window.c

@@ -25,6 +25,10 @@ void ui_window_null_destroy(void *data)
 {
 }
 
+void ui_window_null_set_focused(void *data)
+{
+}
+
 static void ui_window_null_set_visible(void *data,
         bool set_visible)
 {
@@ -32,6 +36,7 @@ static void ui_window_null_set_visible(void *data,
 
 const ui_window_t ui_window_null = {
    ui_window_null_destroy,
+   ui_window_null_set_focused,
    ui_window_null_set_visible,
-   "null",
+   "null"
 };

ui/drivers/win32/ui_win32_window.c

@@ -54,6 +54,12 @@ void ui_window_win32_destroy(void *data)
    DestroyWindow(window->hwnd);
 }
 
+void ui_window_win32_set_focused(void *data)
+{
+   ui_window_win32_t *window = (ui_window_win32_t*)data;
+   SetFocus(window->hwnd);
+}
+
 void ui_window_win32_set_visible(void *data,
         bool set_visible)
 {
@@ -61,6 +67,7 @@ void ui_window_win32_set_visible(void *data,
 
 const ui_window_t ui_window_win32 = {
    ui_window_win32_destroy,
+   ui_window_win32_set_focused,
    ui_window_win32_set_visible,
-   "win32",
+   "win32"
 };

ui/drivers/win32/ui_win32_window.h

@@ -40,6 +40,8 @@ typedef struct ui_window_win32
 void ui_window_win32_set_visible(void *data,
         bool set_visible);
 
+void ui_window_win32_set_focused(void *data);
+
 void ui_window_win32_destroy(void *data);
 
 RETRO_END_DECLS

ui/ui_companion_driver.h

@@ -34,6 +34,7 @@ RETRO_BEGIN_DECLS
 typedef struct ui_window
 {
    void (*destroy)(void *data);
+   void (*set_focused)(void *data);
    void (*set_visible)(void *data, bool visible);
    const char *ident;
 } ui_window_t;