Column header editors are invisible at the default inspector width

In the Window and Web page designers, the Inspector's Column Headers editor for ListBox controls needs a wider panel than the default left sidebar. At the default width the header title text boxes are squeezed to zero width and become invisible, so it looks as though column header titles cannot be edited at all. Users must widen the sidebar by hand to discover the fields.

Studio now defaults the left sidebar to a width that keeps the column editors visible. Saved widths that still match the old default are upgraded once; widths a user deliberately chose are kept, and the sidebar can still be narrowed afterwards.