[Gtk-3.22] Progressbar under Treeview: Minor fixes

* Do not draw progressbar border using box shadows, progressbar is now more flatter.
* Do not use different color for progressbar in disabled state. In transmission, in normal state, progressbar (not selected)
has no color, while in backdrop state it gets it's color back. This shouldn't be happenning.
* Use border for progressbar.through

These fixes are mainly for light variant. Dark variant requires much more work.

Author: khurshid-alam

src/gtk-3.20/scss/widgets/_view.scss

@@ -177,9 +177,6 @@
             border-radius: $roundness;
             border: 1px solid $selected_borders_color;
             background-color: $selected_bg_color;
-            //background-image: linear-gradient(to bottom, $selected_bg_color, darken($selected_bg_color, .1));
-            box-shadow: inset 0 1px if($variant == 'light', transparentize($white, .7), transparentize($white, .85)),
-                              0 1px if($variant == 'light', transparentize($black, .8), transparentize($black, .9));
 
             &:selected {
                 &:focus, & {
@@ -205,10 +202,11 @@
                 }
             }
 
-            &:disabled {
+	    // Do not use different progressbar color for disabled state,
+            /*&:disabled {
                 @include linear-gradient($bg_color);
                 border-color: border_insensitive($bg_color);
-            }
+            }*/
 
             &:backdrop {
                 @if $variant == 'light' {
@@ -223,18 +221,14 @@
         }
 
         &.trough { // progress bar trough in treeviews
-            background-color: transparentize($fg_color, .9);
             border-radius: $roundness;
+	    border: 1px solid alpha(border_normal($bg_color), .5);
+            background-color: transparentize($fg_color, .9);
 
             &:selected {
                 &:focus, & {
-                    background-color: if($variant == 'light', transparentize($selected_fg_color, .7), darken($selected_bg_color, .1));
-
-                    @if $variant == 'light' {
-                        border-width: 1px 0;
-                        border-style: solid;
-                        border-color: $selected_bg_color;
-                    }
+                    background-color: if($variant == 'light', transparentize($bg_color, .7), darken($selected_bg_color, .1));
+                    @if $variant == 'light' { border: 1px solid $selected_borders_color; }
                 }
             }
         }