Tips for Using Attachments

When a component is resized, all attachments are checked; therefore, unnecessary attachments may affect performance. Also, attachment information is stored with the FRAME entry, so unnecessary attachments increase the size of the stored entry.

The same is not true for component size restrictions. Virtually no overhead is paid for these settings. Sometimes, you may want to turn on a fixed size restriction, even if only for documentation purposes; that is, if the attachments are viewed by another person at a later date, they will be more understandable.

This is true even if the master component is grown from the upper left of the window. Therefore, absolute attachments to the top or the left of the master component are unnecessary. Note that this is not true of components in general, only of the master component.

If you know that a container or group component will only be moved and not resized due to attachments to its siblings and parent, then you do not need to define any attachments to the child components of the container or group.

If the attachments are getting too complicated, consider creating a container box just to hold a set of related components. Attach the container to its parent and siblings and set up attachments (if necessary) to the container's children.

It is easy to create a situation that cannot be satisfied when mixing absolute and relative attachments in the same direction. Sometimes such situations are appropriate, but you should take a second look to make sure this is really what you need.

Usually the desired placement of a component after honoring a relative attachment does not exactly align on a row/column boundary, which necessitates a shift of the component to attain the required alignment. This situation can create odd visual effects, and it significantly increases the chance that textual objects will overlap. If you feel you must use relative attachments with text-based objects, be sure to leave space around each component to allow for shifting without creating an overlap situation.

A related problem occurs when a container contains character-aligned objects (widgets) and the container is relatively attached. The container is not character-cell aligned, and when the master component is resized, the widgets often shift within the container.

You can avoid this shifting by creating a dummy character-cell-aligned component (for example, a one-character text field that is protected and nondisplayable). Attach this dummy component to the master component relatively, and then attach the container to the dummy component absolutely. Make sure the absolute attachment is short so that the resulting location of the container is as close to relatively correct as possible.

When the master component is resized, the dummy component will be positioned relatively, and then it will align to a character-cell boundary. Then, the absolute attachment between it and the container will be honored. No shifting will occur within the container either since the net movement of the container is guaranteed to be an integral number of character cells. This guarantee is possible because the master component is always an integral number of character cells in size and the dummy component is always character-cell aligned.

Remember that you can still resize any component without attachments being honored by entering define attachment mode and performing the desired move or resize. This action causes any associated attachments to be redefined instead of honored.

In general, results are usually better when honoring the growth rather than the shrinkage of the master component. You are better off defining your window to be as close to the smallest allowable size and ensuring that you handle size increases gracefully through attachment. The primary reason for this is that if you create a window too large and then try to shrink it, the master component may become too small, and the containing component may also become too small to hold other components.

Avoid very short attachments to a component that contains a component that must be character-cell aligned. These attachments are most likely to be ignored because of the one-half character rule mentioned earlier. Short attachments are acceptable if placement or size variations within ½ character are insignificant and if propagation is not an issue. Such attachments are a concern only when you are attaching to a component that contains an object that must be character-cell aligned.

You can test all attachments while in build mode. Position the components, create the attachments, and save the entry so that the desired placement is not lost (in case the attachments do not work as you expect them). If the attachments do not work, then cancel them, re-edit the frame, and change the attachments appropriately.

Single-directional attachments are usually most appropriate, especially for attachments from parent to child. Sibling attachments can also be made single directional, but be sure to analyze how resizing the master component will affect subcomponents so that you define sibling attachments in the correct direction.

If you want a component to maintain a relative size, attach one side to the parent relatively and set the component-size restriction to fixed relative, instead of attaching both sides relatively. This technique results in significantly fewer attachments if you have many components that are being sized relatively in this manner.

To determine the kind of attachment that is defined for a section, click in the section while you are in define attachment mode. A message will be displayed indicating what kind of attachment is defined there and what it is attached to.