A TAction object is a container for specific action-related topics like events, description, help-topic, icon, shortcut(s). When using TActions in the Action-property of buttons, menus, dialogs, controls it is possible to centralize the effects of mouse-clicks, menu-choices, dialog-selections, shortcuts etc. in a single event handler.
We want to have a TAction that handles opening of some other form. Make sure to have a TActionList on the main form. Doubleclick the TActionList to get the ActionList Editor. Create a new action by hitting the plus-sign. In the Object Inspector, set the name to actSomeAction, set a desired shortcut, a caption to be uses in menu's, an imageindex if a TImageList is connected to the parent ActionList, Hint is hints are to be displayed, helpkeyword and other properties where relevant.
The most important is the OnExecute-event that will be executed if the action is triggered somehow (menu, shortcut, button).
procedure TMyForm.actSomeActionExecute(Sender: TObject); var f: TSomeForm; rv: integer; begin f := TSomeForm.Create( nil ); f.Caption := 'SomeForm'; rv := f.ShowModal(); if rv=mrOk then DoSomethingMeaningful(); f.Free(); end;