Mouse-related Issue in egui\examples\custom_window_frame

[rustbasic]

Title: Mouse-related Issue in egui\examples\custom_window_frame

@emilk
Dear emilk,

In the egui\examples\custom_window_frame,
there is an issue with moving the window using the mouse.
Therefore, I made the following modification to line 109 in egui\examples\custom_window_frame\src\main.rs:

    if title_bar_response.double_clicked() {                                          
        let is_maximized = ui.input(|i| i.viewport().maximized.unwrap_or(false));     
        ui.ctx()                                                                      
            .send_viewport_cmd(ViewportCommand::Maximized(!is_maximized));            
                                                                                      
    }                                                                                 
//    } else if title_bar_response.is_pointer_button_down_on() {                                   
    if title_bar_response.is_pointer_button_down_on() {                               
        ui.ctx().send_viewport_cmd(ViewportCommand::StartDrag);                       
    }                                                                                 

With this modification, the window moves correctly initially.
Even when changing to "maximized" by selecting the icon without double-clicking and returning to the original size,
it moves without any issues.

However, if the screen is changed to "maximized" by double-clicking and then returned to the original size,
attempting to move it again does not work at all.

Thank you,
emilk.

egui version: egui v0.25.0
OS: Windows 10

prev issue:
#3669

[rustbasic]

@emilk

When maximized by pressing the button on the menu and then returning to the original size,
the title can be dragged by clicking it.
However, when minimized by pressing the button on the menu and then returning to the original size,
the title cannot be dragged by clicking it.

It seems to be related to checking and saving the minimized or maximized state.

[emilk]

I don't have a Windows computer, so I would appreciate if you could investigate and make a PR!

[rustbasic]

@emilk
Dear emilk.

If the double_clicked() part of the 102nd line is all commented out and executed,
the title can be clicked and dragged normally.
However, after double-clicking ( or clicking ) the title for no reason, dragging does not work.
The title_bar_response.is_pointer_button_down_on() function returns true normally.
This suggests that there is a problem
with the ui.ctx().send_viewport_cmd(ViewportCommand::StartDrag) function.

/*
    // Interact with the title bar (drag to move window):
    if title_bar_response.double_clicked() {
        let is_maximized = ui.input(|i| i.viewport().maximized.unwrap_or(false));
        ui.ctx()
            .send_viewport_cmd(ViewportCommand::Maximized(!is_maximized));
    }
//    } else if title_bar_response.is_pointer_button_down_on() {
*/
    if title_bar_response.is_pointer_button_down_on() {
        ui.ctx().send_viewport_cmd(ViewportCommand::StartDrag);
    }

This issue is separate from the bug where, after using ui.ctx().send_viewport_cmd() to minimize, it still recognizes it as minimized, preventing dragging.

Thanks, emilk.

egui version: egui v0.25.0 - this issue bug.
egui v0.24.0 or Other Version - normally, no issue.

[axxop]

same #3791