TActionManager in MDI application. Losing actions

Question

I have a MDI application and I'm using TActionManager to manage actions within my application which also means that it contains the actions for my MDIChild forms.

Here's an simple exemple to recreate my problem:

Create a new VCL Forms applications with 2 forms. Form1 & Form2 Drop a TButton and a TActionManager over Form1. Create 2 TActions using TActionManager's PopUp Editor. Set FormStyle := fsMDIForm for Form1. Set FormStyle := fsMDIChild for Form2.

Add this code to correspondant events:

// Form1   
procedure TForm1.Action1Execute(Sender: TObject);
begin
   ShowMessage('Action1');
end;
procedure TForm1.Action2Execute(Sender: TObject);
begin
   ShowMessage('Action2');
end;
procedure TForm1.Button1Click(Sender: TObject);
var
   oForm2: TForm2;
begin
   oForm2 := TForm2.Create(Application);
end;

// Form 2
procedure TForm2.FormClose(Sender: TObject; var Action: TCloseAction);
begin
   Action := caFree;
end;

Drop a TActionToolBar over Form2. Drop Action1 and Action2 over this TActionToolBar using TActionManager PopUp Editor. Save & Run. Click on the button on Form1 to show Form2. Everything works as expected. Now close Form2 and open it back. Actions are missing...

Is there a way to avoid losing my actions knowing that I really need to use TActionManager?

Answer 1

I am going to attempt to explain as best I understand the issue.

First of all, your actions are disconnected not "gone", they still exist. In other words, ActionManager1.ActionCount will still return 2.

With that said, what you are doing at design time is connecting one the action list on one form variable with tool bar on another form variable. In other words. Form1.ActionList is being attached to Form2.ToolBar. That's why it works the first time you run, the next time you create an instance of TForm2, it is no longer the default created Form2 and therefore is not connected to variable Form1. This has been my best guess over the years, and I have experienced similar issues with DataModules.

My answer is, put the action list on the child form. If you need the actions to be shared across all of the child forms, than the action list and tool bar belong on the MDI parent. This is fairly standard for MDI Apps.