completion: use css for row separation

Instead of using a GtkSeparator this uses CSS to style the rows
with a header line. This requires less changes in the scene graph and
also allows us to avoid size request changes, meaning the box will not
jitter as much during updates.

3 files changed, 12 insertions, 14 deletions

diff --git a/gtksourceview/GtkSourceView.css b/gtksourceview/GtkSourceView.css
index f0fe96bc..d38a1580 100644
--- a/gtksourceview/GtkSourceView.css
+++ b/gtksourceview/GtkSourceView.css
@@ -49,6 +49,9 @@ GtkSourceAssistant.completion list row {
   transition: none;
   box-shadow: none;
 }
+GtkSourceAssistant.completion list row.group-leader {
+  border-top: 1px solid @borders;
+}
 GtkSourceAssistant.completion list row:first-child {
   border-top-left-radius: 11px;
   border-top-right-radius: 11px;
diff --git a/gtksourceview/gtksourcecompletionlistbox.c b/gtksourceview/gtksourcecompletionlistbox.c
index a8f7d209..9eaa763f 100644
--- a/gtksourceview/gtksourcecompletionlistbox.c
+++ b/gtksourceview/gtksourcecompletionlistbox.c
@@ -858,7 +858,6 @@ gtk_source_completion_list_box_do_update (GtkSourceCompletionListBox *self,
 	{
 		GtkSourceCompletionProposal *proposal = NULL;
 		GtkSourceCompletionProvider *provider = NULL;
-		GtkWidget *header;
 		gboolean has_alternates = FALSE;
 
 		if (!GTK_SOURCE_IS_COMPLETION_LIST_BOX_ROW (iter))
@@ -866,8 +865,6 @@ gtk_source_completion_list_box_do_update (GtkSourceCompletionListBox *self,
 			continue;
 		}
 
-		header = gtk_list_box_row_get_header (GTK_LIST_BOX_ROW (iter));
-
 		if (state.selected >= 0 && state.position == (guint)state.selected)
 		{
 			gtk_widget_set_state_flags (iter, GTK_STATE_FLAG_SELECTED, FALSE);
@@ -902,13 +899,20 @@ gtk_source_completion_list_box_do_update (GtkSourceCompletionListBox *self,
 			                                             self->show_icons,
 			                                             has_alternates);
 
+			if (last_provider != NULL && provider != last_provider)
+			{
+				gtk_widget_add_css_class (GTK_WIDGET (iter), "group-leader");
+			}
+			else
+			{
+				gtk_widget_remove_css_class (GTK_WIDGET (iter), "group-leader");
+			}
+
 			gtk_widget_show (iter);
-			gtk_widget_set_visible (header, provider != last_provider && last_provider);
 		}
 		else
 		{
 			gtk_widget_hide (iter);
-			gtk_widget_hide (header);
 			_gtk_source_completion_list_box_row_display (GTK_SOURCE_COMPLETION_LIST_BOX_ROW (iter),
 			                                             NULL, NULL, NULL, self->show_icons, FALSE);
 		}
@@ -1016,10 +1020,8 @@ _gtk_source_completion_list_box_set_n_rows (GtkSourceCompletionListBox *self,
 		for (guint i = 0; i < n_rows; i++)
 		{
 			GtkWidget *row;
-			GtkWidget *header;
 
 			row = _gtk_source_completion_list_box_row_new ();
-			header = gtk_list_box_row_get_header (GTK_LIST_BOX_ROW (row));
 
 			gtk_widget_set_can_focus (GTK_WIDGET (row), FALSE);
 
@@ -1030,7 +1032,6 @@ _gtk_source_completion_list_box_set_n_rows (GtkSourceCompletionListBox *self,
 			_gtk_source_completion_list_box_row_set_attrs (GTK_SOURCE_COMPLETION_LIST_BOX_ROW (row),
 			                                               self->font_attrs);
 
-			gtk_box_append (self->box, header);
 			gtk_box_append (self->box, row);
 		}
 
diff --git a/gtksourceview/gtksourcecompletionlistboxrow.c b/gtksourceview/gtksourcecompletionlistboxrow.c
index ea710a32..c64e358b 100644
--- a/gtksourceview/gtksourcecompletionlistboxrow.c
+++ b/gtksourceview/gtksourcecompletionlistboxrow.c
@@ -77,12 +77,6 @@ static void
 gtk_source_completion_list_box_row_init (GtkSourceCompletionListBoxRow *self)
 {
 	gtk_widget_init_template (GTK_WIDGET (self));
-
-  gtk_list_box_row_set_header (GTK_LIST_BOX_ROW (self),
-                               g_object_new (GTK_TYPE_SEPARATOR,
-                                             "orientation", GTK_ORIENTATION_HORIZONTAL,
-                                             "visible", FALSE,
-                                             NULL));
 }
 
 GtkWidget *