[AD] Fullscreen programs losing palette under Windows

[Trent Gamblin <trent@xxxxxxxxxx>]

Under Windows, when an 8-bit fullscreen program is tabbed away from,
then tabbed back to, it loses it's palette.

A potential fix is attached.

Index: src/win/wddfull.c
===================================================================
--- src/win/wddfull.c	(revision 7876)
+++ src/win/wddfull.c	(working copy)
@@ -24,6 +24,7 @@
 static struct BITMAP *init_directx_safe(int w, int h, int v_w, int v_h, int color_depth);
 static void finalize_fullscreen_init(void);
 static void switch_in_fullscreen(void);
+static void switch_out_fullscreen(void);
 
 
 GFX_DRIVER gfx_directx_accel =
@@ -148,7 +149,7 @@
 {
    FALSE,                       // true if driver has backing store
    switch_in_fullscreen,
-   NULL,                        // AL_METHOD(void, switch_out, (void));
+   switch_out_fullscreen,
    NULL,                        // AL_METHOD(void, enter_sysmode, (void));
    NULL,                        // AL_METHOD(void, exit_sysmode, (void));
    NULL,                        // AL_METHOD(void, move, (int x, int y, int w, int h));
@@ -157,7 +158,14 @@
 };
 
 
+/*
+ * When switching away from an 8-bit fullscreen program,
+ * the palette is lost. This stores the palette so it
+ * can be restored when switching back in.
+ */
+static PALETTE saved_palette;
 
+
 /* init_directx_accel:
  *  Initializes the DirectDraw fullscreen hardware-accelerated driver.
  */
@@ -249,5 +257,17 @@
 static void switch_in_fullscreen(void)
 {
    restore_all_ddraw_surfaces();
+   if (_color_depth == 8)
+     set_palette(saved_palette);
 }
 
+
+/* switch_out_fullscreen:
+ *  Handles screen switched out.
+ */
+static void switch_out_fullscreen(void)
+{
+   if (_color_depth == 8)
+      get_palette(saved_palette);
+}
+