dialog fields that auto-copy pastebuffer

7.20: adde/gui/dialog fields that auto-copy pastebuffer:
. when a menu needs additional information,
it launches a dialog .
. often we get the needed info by cut&paste;
so, one shortcut for filling a dialog
is having it listen for the next
cut or copy {ctrl-c, ctrl-x}
then automatically copy the pastebuffer
into the current field,
and finally, transfer dialog focus
to the field where the paste just happened .
. when it does this automation
it also switches itself to the forefront
(but not on top of all other windows;
instead it's alongside the current window
resizing it if needed)
so you'll be reminded in case you forgot
that you were in the middle of a dialog .
document access during a dialog:
. the dialog was launched from a home document;
and we may need access to the home document
because that may be where we can
copy what needs to go into the dialog .
. but if the home document is modified,
that could change the dialog's selection;
and then the dialog is no longer valid,
because it was for a menu item
that may no longer apply to
what's left of the original selection .
. the user should still be able to modify
other parts of the home document
(parts not selected during the dialog).
so, adde must be able to detect
whether just the selection has changed;
eg, put a tag in the doc,
showing where the selection starts,
and the tag includes the size of selection,
along with the hash value .
(if the selection has been changed,
then the selection tag will be gone,
or the hash will be different).

7.20: adde/gui/dual help-run menu items:
. the [?]-icon beside each menu item
is there to show the doc's for an item
rather than launch the item .