[gimp/gimp-2-10] app: allow switching fill type with Alt even when Pattern fill selected.

[Jehan <jehanp src gnome org>]

commit fec11389cb4a1863fcad7d4506f1c77e85adcd17
Author: Jehan <jehan girinstud io>
Date:   Sat Dec 8 10:54:38 2018 +0100

    app: allow switching fill type with Alt even when Pattern fill selected.
    
    Currently in bucket fill tool, the modifier was only switching fg to bg
    and bg to fg, and was doing nothing when pattern was set. I make it
    switch to fg as well (and remember which was the original value).
    
    (cherry picked from commit 5a157bf1ba662891e485b79fbd619736e7669288)

 app/tools/gimpbucketfilltool.c | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)
---
diff --git a/app/tools/gimpbucketfilltool.c b/app/tools/gimpbucketfilltool.c
index bf0f0f243f..e11c9077be 100644
--- a/app/tools/gimpbucketfilltool.c
+++ b/app/tools/gimpbucketfilltool.c
@@ -66,14 +66,17 @@ struct _GimpBucketFillToolPrivate
   GWeakRef            cached_image;
   GWeakRef            cached_drawable;
 
-  GeglBuffer         *fill_mask;
-
   /* For preview */
   GeglNode           *graph;
   GeglNode           *fill_node;
   GeglNode           *offset_node;
 
+  GeglBuffer         *fill_mask;
+
   GimpDrawableFilter *filter;
+
+  /* Temp property save */
+  GimpBucketFillMode  fill_mode;
 };
 
 /*  local function prototypes  */
@@ -621,18 +624,27 @@ gimp_bucket_fill_tool_modifier_key (GimpTool        *tool,
 
   if (key == GDK_MOD1_MASK)
     {
-      switch (options->fill_mode)
+      if (press)
         {
-        case GIMP_BUCKET_FILL_FG:
-          g_object_set (options, "fill-mode", GIMP_BUCKET_FILL_BG, NULL);
-          break;
+          GIMP_BUCKET_FILL_TOOL (tool)->priv->fill_mode = options->fill_mode;
+          switch (options->fill_mode)
+            {
+            case GIMP_BUCKET_FILL_FG:
+              g_object_set (options, "fill-mode", GIMP_BUCKET_FILL_BG, NULL);
+              break;
 
-        case GIMP_BUCKET_FILL_BG:
-          g_object_set (options, "fill-mode", GIMP_BUCKET_FILL_FG, NULL);
-          break;
+            default: /* GIMP_BUCKET_FILL_BG && GIMP_BUCKET_FILL_PATTERN */
+              g_object_set (options, "fill-mode", GIMP_BUCKET_FILL_FG, NULL);
+              break;
 
-        default:
-          break;
+              break;
+            }
+        }
+      else /* release */
+        {
+          g_object_set (options, "fill-mode",
+                        GIMP_BUCKET_FILL_TOOL (tool)->priv->fill_mode,
+                        NULL);
         }
     }
   else if (key == gimp_get_toggle_behavior_mask ())