focusWidget

pub fn focusWidget(self: *Self, id: ?Id, subwindow_id: ?Id, event_num: ?u16) void {
    self.scroll_to_focused = false;
    const swid = subwindow_id orelse self.subwindows.current_id;
    if (self.subwindows.get(swid)) |sw| {
        if (sw.focused_widget_id == id) return;
        sw.focused_widget_id = id;
        if (event_num) |en| {
            self.focusEvents(en, sw.id, sw.focused_widget_id);
        }
        self.refreshWindow(@src(), null);

        var kb_nav = false;

        if (id) |wid| {
            self.scroll_to_focused = true;

            for (self.tab_index_prev.items) |ti| {
                if (ti.windowId == sw.id and ti.widgetId == wid) {
                    kb_nav = true;
                }
            }

            if (self.last_registered_id_this_frame == wid) {
                self.last_focused_id_this_frame = wid;
                self.last_focused_id_in_subwindow = wid;
            } else {
                // walk parent chain
                var iter = self.current_parent.data().iterator();
                while (iter.next()) |wd| {
                    if (wd.id == wid) {
                        self.last_focused_id_this_frame = wid;
                        self.last_focused_id_in_subwindow = wid;
                        break;
                    }
                }
            }
        }

        if (!kb_nav) {
            var closest: f32 = 0;
            var found_left: bool = false;
            for (self.tab_index_prev.items) |ti| {
                if (ti.windowId == sw.id) {
                    const diff = self.mouse_pt.diff(ti.pt);
                    const d = diff.x * diff.x + diff.y * diff.y;
                    if (diff.x >= 0 and ((diff.y >= 0 and diff.y <= diff.x) or (diff.y < 0 and @abs(diff.y) <= diff.x * 0.1))) {
                        if (sw.kb_restart_widget_id == null or !found_left or d < closest) {
                            sw.kb_restart_widget_id = ti.widgetId;
                            closest = d;
                        }
                        found_left = true;
                    } else if (!found_left) {
                        if (sw.kb_restart_widget_id == null or d < closest) {
                            sw.kb_restart_widget_id = ti.widgetId;
                            closest = d;
                        }
                    }
                }
            }
        }
    }
}