css: Track selected state separately

Like the previous change, this reduces the number of
css nodes reacting to parent-state changes. The remaining
parent-state cases here are due to :link.

Before (numbers from widget-factory with Adwaita):
2247 nodes
class 612
name 2246
id 2
first-child 148
last-child 156
state 2245
hover 562
disabled 859
backdrop 1080
sibling-name 63
sibling-disabled 51
parent-class 586
parent-name 788
parent-id 2
parent-first-child 78
parent-last-child 78
parent-state 236
parent-hover 5
parent-disabled 91
parent-backdrop 4

After:
2247 nodes
class 612
name 2246
id 2
first-child 148
last-child 156
state 2245
hover 562
disabled 859
backdrop 1080
selected 579
sibling-name 63
sibling-disabled 51
parent-class 586
parent-name 788
parent-id 2
parent-first-child 78
parent-last-child 78
parent-state 115
parent-hover 5
parent-disabled 91
parent-backdrop 4
parent-selected 144

1 files changed, 4 insertions, 1 deletions

diff --git a/gtk/gtkcssnode.c b/gtk/gtkcssnode.c
index dc535e6332..7af6c7ab93 100644
--- a/gtk/gtkcssnode.c
+++ b/gtk/gtkcssnode.c
@@ -1153,9 +1153,12 @@ gtk_css_node_set_state (GtkCssNode    *cssnode,
         change |= GTK_CSS_CHANGE_DISABLED;
       if (states & GTK_STATE_FLAG_BACKDROP)
         change |= GTK_CSS_CHANGE_BACKDROP;
+      if (states & GTK_STATE_FLAG_SELECTED)
+        change |= GTK_CSS_CHANGE_SELECTED;
       if (states & ~(GTK_STATE_FLAG_PRELIGHT |
                      GTK_STATE_FLAG_INSENSITIVE |
-                     GTK_STATE_FLAG_BACKDROP))
+                     GTK_STATE_FLAG_BACKDROP |
+                     GTK_STATE_FLAG_SELECTED))
         change |= GTK_CSS_CHANGE_STATE;
 
       gtk_css_node_invalidate (cssnode, change);