[geary: 1/2] composer: Center "drop files here" message

[Michael Gratton <mjog src gnome org>]

commit b39182b719043a300291530fe4aa4b362840b489
Author: James Westman <flyingpimonster gmail com>
Date:   Fri Jan 3 17:02:44 2020 -0600

    composer: Center "drop files here" message
    
    The "Drop files here to add them as attachments" message was not
    centered as it should have been, because the "expand" child property was
    reset to false when it was removed/readded to its parent.

 src/client/composer/composer-widget.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/client/composer/composer-widget.vala b/src/client/composer/composer-widget.vala
index e46bc6f3..871561b4 100644
--- a/src/client/composer/composer-widget.vala
+++ b/src/client/composer/composer-widget.vala
@@ -1202,7 +1202,7 @@ public class Composer.Widget : Gtk.EventBox, Geary.BaseInterface {
         if (visible) {
             int height = hidden_on_attachment_drag_over.get_allocated_height();
             this.hidden_on_attachment_drag_over.remove(this.hidden_on_attachment_drag_over_child);
-            this.visible_on_attachment_drag_over.add(this.visible_on_attachment_drag_over_child);
+            this.visible_on_attachment_drag_over.pack_start(this.visible_on_attachment_drag_over_child, 
true, true);
             this.visible_on_attachment_drag_over.set_size_request(-1, height);
         } else {
             this.hidden_on_attachment_drag_over.add(this.hidden_on_attachment_drag_over_child);