[gtk: 1/2] theme: Use -gtk-icon-filter for full-color icons

[Matthias Clasen <matthiasc src gnome org>]

commit c6483d431f1c18a371da8f7f79d049235468731e
Author: nana-4 <hnmaigo gmail com>
Date:   Sun May 31 06:37:06 2020 +0900

    theme: Use -gtk-icon-filter for full-color icons
    
    Not for symbolic icons.
    
    Don't apply `-gtk-icon-filter: opacity(0.5);` to the symbolic icons as
    they already have the "gray" colors indicating the disabled state.
    Symbolic icons can be styled using the `color` property.
    
    Also remove the obsolete comment.

 gtk/theme/Default/_common.scss | 20 ++++++--------------
 1 file changed, 6 insertions(+), 14 deletions(-)
---
diff --git a/gtk/theme/Default/_common.scss b/gtk/theme/Default/_common.scss
index 9b44517af5..83692f5e97 100644
--- a/gtk/theme/Default/_common.scss
+++ b/gtk/theme/Default/_common.scss
@@ -39,19 +39,9 @@ dnd {
   -gtk-icon-size: 32px;
 }
 
-/*
-   These wildcard seems unavoidable, need to investigate.
-   Wildcards are bad and troublesome, use them with care,
-   or better, just don't.
-   Every time a wildcard is used a kitten dies, painfully.
-*/
-
-spinner:disabled,
-arrow:disabled,
-scrollbar:disabled,
-check:disabled,
-radio:disabled,
-treeview.expander:disabled { -gtk-icon-filter: opacity(0.5); }
+image:disabled {
+  -gtk-icon-filter: opacity(0.5);
+}
 
 .view,
 %view {
@@ -509,7 +499,8 @@ button {
         @include button(backdrop);
 
         transition: $backdrop_transition;
-        -gtk-icon-filter: none;
+
+        &:not(:disabled) { -gtk-icon-filter: none; }
 
         &:active,
         &:checked { @include button(backdrop-active); }
@@ -525,6 +516,7 @@ button {
 
     &:disabled {
       @include button(insensitive);
+      -gtk-icon-filter: opacity(0.5);
 
       &:active,
       &:checked { @include button(insensitive-active); }