Delphi - TFrame Components

Creating components from scratch is covered on other pages. However, sometimes it is useful to reuse a collection of existing components and related code. There are several ways to do this, each with its own pros and cons. This page discusses of the TFrame method.

Note: There is something weird about the technique described on this page. When I wrote it, this was correct - however, now (07-2014) it is not. I am trying to figure out what happened .. and why.

Basics | Technique | Naming Issue | Inheritance | Initialization | Multiselect Handles


A TFrame is designed just like a form Advantages (with respect to a custom component) Disadvantages (with respect to a custom component)

TFrame and TForm are similar in many ways. They are both descendents of TScrollingWinControl and both are associated with dfm files - text files that define the properties associated with buttons and other controls. The TFrame does not have a border (BorderStyle) or the OnCreate event. Otherwise, they are similar.


Palette page is the toolbar tab it will be placed on .. the default is Templates.

The icon can be changed to any 24x24 bitmap (*.bmp file).

The original class name was TFrame2 .. this prompt changes it to what you enter .. sort of. Apparently, the word Template will also be associated with it. I am not sure what function (if any) this performs.

(The number in the default name depends on the number of unsaved units that are open. The default form is '1', the frame is '2'.)

Naming Issue

When a TFrame is placed on a form, the default name for the first occurrence starts with a "T", the later occurrences do not. Though it doesn't really hurt anything .. this is a Delphi design problem.


Frames are special types of objects. At design time, the user is able to select individual components and set their properties .. including the events. The main reason I use frames is so that some fairly complex code can be reused without having to test it in every application. With regular objects, when a method is overridden, the underlying code is executed using inherited. However, TFrames work a bit differently because the event code is owned by the frame - not the object. The following code (automatically created when double clicking a component on the frame) shows how the inherited code is called.


One of the important differences between TFrame and TForm is the OnCreate event - TForm has it, TFrame doesn't.

One solution is to override the frame's Loaded method. (TComponent.Loaded should be left protected.)

This is better than having to remember to place something in the form's OnCreate event. However, there are 2 items to be aware of

Multiselect Handles

At design time, when a control is selected, 8 black sizing handles (squares) are displayed. When several controls are selected, 4 grey handles are displayed. For a number of containers that accept components (frames, forms, panels, and the like), the 8 black handles are rendered on top of the sub-components .. but the 4 grey handles are displayed behind them. As a result, if a frame (or similar container) has components in the corners, the grey handles are very difficult to see.

Therefore, it is important that the frame be a bit larger than the components in it. In particular, none of the components should touch the corners of the frame. A border of 2 or 3 pixels makes a big difference.

Author: Robert Clemenzi -
URL: http:// / user / clemenzi / technical / Languages / Delphi / TFrame.html