About implementing custom window drag-and-drop

[zhangxichang]

struct App;
impl App {
    fn new() -> Self {
        Self
    }
}
impl eframe::App for App {
    fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
        egui::TopBottomPanel::top("MenuBar").show(ctx, |ui| {
            ui.horizontal(|ui| {
                if ui.button("Close").clicked() {
                    ctx.send_viewport_cmd(egui::ViewportCommand::Close);
                }
                let (response, _) = ui.allocate_painter(ui.available_size(), egui::Sense::drag());
                if response.dragged() {
                    if let Some(outer_rect) = ui.input(|is| is.viewport().outer_rect) {
                        ctx.send_viewport_cmd(egui::ViewportCommand::OuterPosition(
                            outer_rect.left_top() + response.drag_delta(),
                        ));
                    }
                }
            });
        });
        egui::CentralPanel::default().show(ctx, |ui| {});
    }
}

Here is my code to implement window drag and drop. However, there is a problem that the window will blur during drag and drop, and the window will not move in sync with the mouse.
Here is my code to implement window drag and drop.

[arcana6264]

You may try ctx.send_viewport_cmd(egui::ViewportCommand::StartDrag);

[Hifive55555]

thanks it works, but i also wonder why the solution above failed