[gnome-shell-sass] folderIcon: Add visual drag-over feedback

[Florian Müllner <fmuellner src gnome org>]

commit c38a7b13207a2849ac5772eb348dc87527c3272c
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Mon Jul 1 21:37:35 2019 -0300

    folderIcon: Add visual drag-over feedback
    
    WIP: This is not exactly what was discussed on IRC, but
    it's looking alright as a first iteration. Design feedback
    welcomed.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/664

 _common.scss | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/_common.scss b/_common.scss
index 5e377df..8731ba4 100644
--- a/_common.scss
+++ b/_common.scss
@@ -1514,6 +1514,9 @@ StScrollBar {
       border-image: none;
       background-image: none;
     }
+    &:drop .overview-icon {
+      background-color: transparentize($selected_bg_color,.15);
+    }
     &:active .overview-icon,
     &:checked .overview-icon {
       background-color: transparentize(darken($osd_bg_color,10%), 0.5);