Request: Allow Full Control Over MessageDialog Buttons

bad_wolf

Hi Garry,

While working with MessageDialog in WeightCatcher, I noticed something that I think may be a limitation in the current implementation.

When I want to display only the Cancel button, for example, I leave ActionButtonCaption empty and only specify CancelButtonCaption:

Var dlg As New MessageDialog
dlg.ActionButtonCaption = ""
dlg.CancelButtonCaption = "Cancel"
dlg.AlternateActionButtonCaption = ""
dlg.Show()

I would expect this to display only the Cancel button. However, an OK Action button is automatically added as well.

This means that the developer cannot independently determine which of the Action, Cancel and Alternate buttons should be displayed.

I think it would be preferable to leave this decision entirely to the application developer. Depending on the purpose of the dialog, the developer may want to display an Action/OK button, a Cancel button, an Alternate button, any combination of these, or perhaps even no button at all. MessageDialog should ideally not add a button that the developer did not request.

Perhaps an empty caption could mean that the corresponding button is not displayed, or alternatively each button could have its own visibility property.

It would give developers much more control over the behaviour of MessageDialog while still keeping the API simple.

Kind regards,

ChrisRequest: Allow Full Control Over MessageDialog Buttons

Garry

Hi Chris,

You are correct: this is a limitation of the current MessageDialog implementation. The Action button is presently always created, whereas empty Cancel and Alternate captions hide those buttons.

I propose changing the behaviour as follows:

An empty ActionButtonCaption hides the Action button.
An empty CancelButtonCaption continues to hide the Cancel button.
An empty AlternateActionButtonCaption continues to hide the Alternate button.
The default values remain unchanged, so a new MessageDialog still displays a single OK Action button.
At least one button must have a non-empty caption. Calling Show() with all three captions empty will raise an InvalidArgumentException. A modal dialog without any way to complete it would be ambiguous and potentially inaccessible.
Closing the dialog using its title-bar close button or Escape will return MessageDialogButton.Cancel when a Cancel button is present. Otherwise, it will return the first available non-cancel result.

This would support the useful case in your example:

Var dlg As New MessageDialog
dlg.ActionButtonCaption = ""
dlg.CancelButtonCaption = "Cancel"
dlg.Show()

That would display only the Cancel button.

I prefer using an empty caption to control visibility rather than adding separate visibility properties. Empty captions already hide the Cancel and Alternate buttons, so applying the same rule consistently to all three keeps the API small and predictable.

I would not support a completely buttonless MessageDialog. For that kind of interface (such as a progress display that closes itself) a custom Window would be more appropriate.

Does this sound like the right balance to everyone?

bad_wolf

Hello Garry,

Thank you for your reply and considering my request. Your suggestion is acceptable without any problem.

You are correct, when no buttons are necessary, it is better to create a custom window.

Kind regards,

Chris

Garry

I’ve implemented this for the next Objo Studio release: https://feedback.objo.dev/feature/1258

An empty caption now hides any of the three buttons, including the Action button. Your example will therefore display only the Cancel button:

Var dlg As New MessageDialog
dlg.ActionButtonCaption = ""
dlg.CancelButtonCaption = "Cancel"
dlg.AlternateActionButtonCaption = ""
dlg.Show()

The existing defaults remain unchanged, so a newly created MessageDialog still displays a single OK Action button.

A dialog must have at least one button. If all three captions are empty, Show() raises an InvalidArgumentException rather than displaying a buttonless modal dialog.

Closing the dialog using Escape or its title-bar close button returns MessageDialogButton.Cancel when a Cancel button is configured. Otherwise, it returns the available Action or Alternate result.

bad_wolf

Garry
Thank you Garry, this is great!

Kind regards,

Chris