Call TSXFlush after setting DGA palette, so it updates immediately.

dlls/ddraw/dpalette/dga.c

diff --git a/dlls/ddraw/dpalette/dga.c b/dlls/ddraw/dpalette/dga.c
index 4ffdb85..698a491 100644
--- a/dlls/ddraw/dpalette/dga.c
+++ b/dlls/ddraw/dpalette/dga.c
@@ -56,6 +56,7 @@
 	This->palents[start+i].peFlags = palent[i].peFlags;
     }
     ddpriv->InstallColormap(display,DefaultScreen(display),dppriv->cm);
+    TSXFlush(display);
     return DD_OK;
 }
 ICOM_VTABLE(IDirectDrawPalette) dga_ddpalvt = 

dlls/ddraw/dsurface/dga.c

diff --git a/dlls/ddraw/dsurface/dga.c b/dlls/ddraw/dsurface/dga.c
index 1ea2a0f..486db6d 100644
--- a/dlls/ddraw/dsurface/dga.c
+++ b/dlls/ddraw/dsurface/dga.c
@@ -109,6 +109,7 @@
 	    dib->colorMap = This->s.palette ? This->s.palette->screen_palents : NULL;
 	    GDI_HEAP_UNLOCK(This->s.DIBsection);
 	}
+	TSXFlush(display);
     }
     return DD_OK;
 }