Description Bob Foster 2003-05-02 15:39:51 EDT

This is a screwball bug that took hours to run down.

Three new preference pages were behaving very oddly.

All three page classes shared the same base class; they differed only in two
text constants set in the subclass constructors. When preferences were
shown, clicking (in the outline) on any page of the three displayed it
normally. But clicking on either of the other two showed only a blank page.
It did not matter which of the three pages were selected first; it always
displayed normally, and the remaining two showed as blank.

To add to the confusion, I have a number of other preference pages, all of
which displayed normally. Selecting the others had no effect on the "blank"
page problem. Except one. If I displayed that one other page at any time,
all three of the pages in question now displayed normally.

If I had hair, I'd have torn it. It was certainly not obvious what about
that "magic" page that "fixed" the problem. But by trial and error, I found it.

All preference pages use GridLayout. The "blank page" phenomenon showed
itself unless and until I selected a page that contained a control for which
GridData.FILL_HORIZONTAL was set. Once that page was drawn, all pages worked
as expected.

Adding GridData.FILL_HORIZONTAL to one of the controls in the base class of
the three page classes in question fixed the problem for all three.