apprt/gtk-ng: address feedback

src/apprt/gtk-ng/class/application.zig

@@ -1727,20 +1727,20 @@ const Action = struct {
         // Find a quick terminal window.
         const list = gtk.Window.listToplevels();
         defer list.free();
-        const elem_: ?*glib.List = list.findCustom(null, struct {
-            fn callback(data: ?*const anyopaque, _: ?*const anyopaque) callconv(.c) c_int {
-                const ptr = data orelse return 1;
-                const gtk_window: *gtk.Window = @ptrCast(@alignCast(@constCast(ptr)));
-                const window = gobject.ext.cast(
+        if (ext.listFind(gtk.Window, list, struct {
+            fn find(gtk_win: *gtk.Window) bool {
+                const win = gobject.ext.cast(
                     Window,
-                    gtk_window,
-                ) orelse return 1;
-                if (window.isQuickTerminal()) return 0;
-                return 1;
+                    gtk_win,
+                ) orelse return false;
+                return win.isQuickTerminal();
             }
-        }.callback);
-        const elem = elem_ orelse return null;
-        return @ptrCast(@alignCast(elem.f_data));
+        }.find)) |w| return gobject.ext.cast(
+            Window,
+            w,
+        ).?;
+
+        return null;
     }
 
     pub fn toggleMaximize(target: apprt.Target) void {

src/apprt/gtk-ng/ext.zig

@@ -6,6 +6,7 @@
 const std = @import("std");
 const assert = std.debug.assert;
 
+const glib = @import("glib");
 const gobject = @import("gobject");
 const gtk = @import("gtk");
 
@@ -23,6 +24,24 @@ pub fn boxedFree(comptime T: type, ptr: ?*T) void {
     );
 }
 
+/// A wrapper around `glib.List.findCustom` to find an element in the list.
+/// The type `T` must be the guaranteed type of every list element.
+pub fn listFind(
+    comptime T: type,
+    list: *glib.List,
+    comptime func: *const fn (*T) bool,
+) ?*T {
+    const elem_: ?*glib.List = list.findCustom(null, struct {
+        fn callback(data: ?*const anyopaque, _: ?*const anyopaque) callconv(.c) c_int {
+            const ptr = data orelse return 1;
+            const v: *T = @ptrCast(@alignCast(@constCast(ptr)));
+            return if (func(v)) 0 else 1;
+        }
+    }.callback);
+    const elem = elem_ orelse return null;
+    return @ptrCast(@alignCast(elem.f_data));
+}
+
 /// Wrapper around `gtk.Widget.getAncestor` to get the widget ancestor
 /// of the given type `T`, or null if it doesn't exist.
 pub fn getAncestor(comptime T: type, widget: *gtk.Widget) ?*T {