[Lazarus] Inconsistent results from MessageDlg()

[Hans-Peter Diettrich]

patspiper schrieb:
> On 22/04/12 16:06, Bart wrote:
>> On 4/22/12, patspiper<patspiper at gmail.com>  wrote:
>>> But I have a slightly different suggestion:
>>> 2- Escape key should first check if any button has Cancel=true, and use
>>> that button's modal result. Otherwise, mrCancel is in order as the user
>>> is running away from answering the dialog.
>> AFAIK, no Button has Escape = True (maybe except for mbCancel) in
>> TPromptDialog.CreateMessageDialog.
> IIRC you mentioned that possibility in your OP. If no button has 
> Cancel=true then there are 2 options:
> - Escape key returns mrCancel
> - Escape key has no effect unless mbCancel button is there
> - Escape key has no effect whatsoever.
>>
>>> 3- [x] should either return mrCancel, or mimic the Escape key. The
>>> latter is the more logical choice, as the programmer has intentionally
>>> defined the action (by setting a button's Cancel to true) if the user
>>> wants to run away.
>> Not the case, as stated above.
>> User (as in application programmer) has no influence over this for 
>> MessageDlg.
> Options for [x]:
> - Suppress it (don't show it)
> - Mimic Escape key
> - return mrCancel

IMO we should consider the real control flow. When a button with a 
ModalResult<>mrNone is clicked, the modal form should close and return 
this value. Here the VCL is flawed, because it closes the form when a 
button with Kind=bkClose is clicked, *without* returning the assigned 
(or an implied) button.ModalResult.

When a modal form can be closed by other means, because an OS or 
widgetset does allow this, then also a defined ModalResult should be 
returned - maybe mrNone or mrCancel (to be defined). Eventually the 
default ModalResult could be assigned by the caller, *prior* to calling 
ShowModal.

DoDi