[gimp] app: clip floating selection to layers with no alpha channel

[Ell <ell src gnome org>]

commit 1c67395c21aa0d4177ec7a3eaab889e46e7fee81
Author: Ell <ell_se yahoo com>
Date:   Thu Oct 3 22:09:43 2019 +0300

    app: clip floating selection to layers with no alpha channel
    
    Alawys clip a floating selection to its base layer, if the layer
    has no alpha channel.  This avoids arbitrarily filling the extended
    regions of the layer with, or compositing the floating selection
    against, black color.
    
    This is a temporary solution.  Ideally, we'd automatically add an
    alpha channel to the layer as necessary.

 app/core/gimpdrawable-floating-selection.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/app/core/gimpdrawable-floating-selection.c b/app/core/gimpdrawable-floating-selection.c
index 53a887a9ca..f16d4bfcb0 100644
--- a/app/core/gimpdrawable-floating-selection.c
+++ b/app/core/gimpdrawable-floating-selection.c
@@ -337,7 +337,8 @@ gimp_drawable_sync_fs_filter (GimpDrawable *drawable)
   gimp_item_get_offset (GIMP_ITEM (fs), &fs_off_x, &fs_off_y);
 
   if (gimp_item_get_clip (GIMP_ITEM (drawable), GIMP_TRANSFORM_RESIZE_ADJUST) ==
-      GIMP_TRANSFORM_RESIZE_CLIP)
+      GIMP_TRANSFORM_RESIZE_CLIP ||
+      ! gimp_drawable_has_alpha (drawable))
     {
       gegl_node_set (
         private->fs_crop_node,