Answering the comment to provide a reason why to use frames:
I would consider frames to be building blocks of the GUI, with design time combination of existing components to more advanced components. Before Delphi 5 one would have used a TCustomPanel
descendant with child controls and registered this as the new component, ready to be dropped onto a form. Frames allow for the same thing with less hassle.
They allow you to concentrate on developing exactly the functionality you need, and nothing more. Done right you can then embed them into tab control sheets, into modal or modeless dialogs, into MDI child frames and into standard frames. You can even add several of them into one form - something one would probably not do with embedded forms. The point is that for maximum reusability a layered approach is often necessary, and frames help with that.
A frame is fit for embedding from the go. A form has to be adapted to not show a caption bar and border, normally one would override the CreateParams()
and adjust the window style accordingly. There are a lot more form properties in the inspector that just don't make sense for an embedded form. IMHO one should use the most basic and generic entity that suffices. A form just is much more than a control container for embedding.
OTOH I don't know of any disadvantage of embedding a frame that embedding a form wouldn't have.
Edit:
There's a comment regarding events like OnCreate
or OnShow
that frames don't have. Actually, I'd consider that another advantage of frames, as event handlers don't have parameters, so a lot of stuff gets hard-coded in forms, necessarily.
Consider the case of per-user settings: in OnCreate
there's not much information available, so one invariably ends up using a constant or the name of the form for the INI file section, making it very hard or even impossible to reuse the form or to create several instances of it. With frames on the other hand a method LoadSettings
is the obvious way to do it, and it can carry the necessary parameters. That way control is returned to where it belongs, to the container of the embedded frame / form. Reusability is only possible if the behaviour can be adjusted from the outside.
For contained objects that are not components and need to be lifetime-managed, there are for example AfterConstruction
and BeforeDestruction
.