gtk: drag overlay toggle

src/apprt/gtk/class/surface.zig

@@ -3650,6 +3650,21 @@ pub const Surface = extern struct {
         };
     }
 
+    fn closureShouldDragHandleBeShown(
+        _: *Self,
+        config_: ?*Config,
+        is_split: c_int,
+    ) callconv(.c) c_int {
+        const config = config_ orelse return @intFromBool(false);
+
+        const shown = switch (config.get().@"drag-handle") {
+            .always => true,
+            .auto => is_split != 0,
+            .never => false,
+        };
+        return @intFromBool(shown);
+    }
+
     fn surfaceDragPrepare(
         src: *gtk.DragSource,
         x: f64,
@@ -3722,7 +3737,6 @@ pub const Surface = extern struct {
         const dropped = self.core().?.app.findSurfaceByID(dropped_id) orelse return;
         const from = dropped.rt_surface.gobj();
 
-        // TODO: Find a better way to access the split tree from here
         const st = ext.getAncestor(
             SplitTree,
             self.as(gtk.Widget),
@@ -3892,6 +3906,7 @@ pub const Surface = extern struct {
             class.bindTemplateCallback("search_changed", &searchChanged);
             class.bindTemplateCallback("search_next_match", &searchNextMatch);
             class.bindTemplateCallback("search_previous_match", &searchPreviousMatch);
+            class.bindTemplateCallback("should_drag_handle_be_shown", &closureShouldDragHandleBeShown);
             class.bindTemplateCallback("surface_drag_prepare", &surfaceDragPrepare);
             class.bindTemplateCallback("surface_drag_begin", &surfaceDragBegin);
             class.bindTemplateCallback("surface_drop", &surfaceDrop);

src/apprt/gtk/ui/1.2/surface.blp

@@ -232,6 +232,7 @@ Overlay terminal_page {
   CenterBox drag_handle {
     halign: fill;
     valign: start;
+    visible: bind $should_drag_handle_be_shown(template.config, template.is-split) as <bool>;
 
     styles [
       "drag-handle",