Created attachment 5905 
screenshot of tabwin

build: git master on debian/testing

An icon with transparency is drawn in tabwin offset from its expected position, see the attached screenshot (third icon, Gnome Commander, the app provides just one 48x48px png icon).

This behaviour started from commit 6a7aff593d752da525aba0098572a2d9d20d0e86 'Use XRender for scaling down window pixmaps'

I found this could be fixed by reverting this part of the commit:

diff --git a/src/icons.c b/src/icons.c
index 1105107..40ebd41 100644
--- a/src/icons.c
+++ b/src/icons.c
@@ -423,9 +423,9 @@ get_pixbuf_from_pixmap (GdkScreen *gscreen, Pixmap xpixmap, guint src_x, guint s
}
cmap = get_cmap (drawable, gscreen);
-
- retval = gdk_pixbuf_get_from_drawable (NULL, drawable, cmap, src_x, src_y,
- dest_x, dest_y, width, height);
+ retval = gdk_pixbuf_new (GDK_COLORSPACE_RGB, TRUE, 8, width, height);
+ gdk_pixbuf_get_from_drawable (retval, drawable, cmap, src_x, src_y,
+ dest_x, dest_y, width, height);



Also fixed by passing FALSE to has_alpha in the gdk_pixbuf_new call.