---

FilterDialog and ModalDialog Limitations (2/5/96)

Q: After closing a view that was opened with theView:FilterDialog(), the part of the screen that was not covered by the theView no longer accepts any pen input. theView is a protoFloatNGo. Is there some trick?

A: There is a problem with FilterDialog and ModalDialog when used to open views that are not immediate children of the root view. At this point we're not sure if we'll be able to fix the problem.

You must not use FilterDialog or ModalDialog to open more than one non-child-of-root view at a time. Opening more than one at a time with either of these messages causes the state information from the first to be overwritten with the state information from the second. The result will be a failure to exit the modality when the views are closed.

Here are some things you can do to avoid or fix the problem with FilterDialog.

Redesign your application so that your modal slips are all children of the root view, created with BuildContext. This is the best solution because it avoids awkward situations when the child of an application is system-modal. (Application subviews should normally be only application-modal.)

Use the ModalDialog message instead of FilterDialog. ModalDialog does not have the child-of-root bug. (FilterDialog is preferred, since it uses fewer system resources and is faster.)

Here is some code you can use to work around the problem much like a potential patch would. (This code should be safe if a patch is madethe body of the if statement should not execute on a corrected system.)

view:FilterDialog();
if view.modalState then
    begin
        local childOfRoot := view;
        while childOfRoot:Parent() <> GetRoot() do
            childOfRoot := childOfRoot:Parent();
        childOfRoot.modalState := view.modalState;
    end;

This only needs to be done if the view that you send the FilterDialog message to is not an immediate child of the root. You can probably improve the efficiency in your applications, since the root child is ususally your application's base view, which is a "well known" view. That is, you may be able to re-write the code as follows:

view:FilterDialog();
if view.modalState then
    base.modalState := view.modalState;