fix(gtk3): progressbar inside treeview

gtk-3.0/scss/widgets/_view.scss

@@ -126,6 +126,31 @@
             background-color: $base_color;
             background-image: none;
         }
+
+        .progressbar,
+        .progressbar:selected,
+        .progressbar:selected:focus {
+            @include linear-gradient($selected_bg_color);
+            border: 1px solid mix($selected_bg_color, $selected_fg_color, .2);
+        }
+
+        .trough,
+        .trough:selected,
+        .trough:selected:focus {
+            background-color: mix($bg_color, $base_color, .5);
+            border: 1px solid $bg_color;
+        }
+
+        .progressbar:insensitive,
+        .progressbar:insensitive:insensitive {
+            @include linear-gradient($bg_color);
+            border-color: $bg_color;
+        }
+
+        .trough:insensitive,
+        .trough:insensitive:insensitive {
+            background-color: $base_color;
+        }
     }
 }