ListSelector Enhancements: Web App support and Optional Add/Delete

[OhHey-ItsDave]

Suggested addutions that could be made to the single pane ListSelector widget to improve usability.

1. The single pane ListSelector uses listdlg() when adding options from the Items property to the Value property (making options visible to be reordered). The listdlg() function is not supported by Web Apps as noted on the "Web App Limitations and Unsupported Functionality" page. An alternate to the ListSelector that works with Web Apps would be very useful.

2. The Add/Delete/Move Up/Move Down buttons for the single pane ListSelector are invisible until one of the options in the list is selected, desired to have them be visible initially. Examples page on File Exchange notes that reordering buttons can be made optional, could not locate property that controls this. Would like option to also make the Add/Delete buttons optional to use widget purely to reorder Items in the list.