Selecting text in URL bar is broken in FF 50 [LINUX]

[kreemoweet]

For several years I have used a script that takes a text string obtained by clicking (once) in Firefox's address bar. Doing that selects the text
and puts it in the "primary X selection buffer" (as I've heard it called). Since updating to FF 50, this action is frequently broken.
I get the following error message in my .x-session-errors file:

"Gtk-Warning **: Failed to set text from markup due to error parsing markup: Error on line 1: Entity did not end with a semicolon; most likely you
used an ampersand character without intending to start an entity - escape ampersand as &"

I do believe that the text in FF's address bar is not "markup", it is a display of plain text, and should be identified as such when FF passes it to the relevant
operating system "clipboard" routines. In other words, the content should be transmitted exactly as it appears. Am I wrong? None of the ampersands in my
collection of URL's (i.e. bookmarks) have been "entity-fied", and they all work just fine.

EDIT: Well, nevermind; it seems this is a bug in the application receiving the clipboard text (Matedialog). As often as ampersands occur in URL's, it seems
an amazing coincidence that my script never ran into one before FF 50 came out, and then encountered several in a row. The fix was to remove the
"mate-dialog" package and install and use the "zenity" package dialogs. The former seems to be a weaksauce, and buggy, version of the latter.