And now $gtktextentryish is unfazed that its data value has changed underneath it.

Hi,

What value does $gtktextentryish display, does it display "Some value" or something else?

http://cpansearch.perl.org/src/XAOC/Gtk2-1.2498/t/GtkEntryBuffer.t doesn't show Gtk2::EntryBuffer->new taking a reference, and neither does https://github.com/Programmica/perl-gtk3-examples/blob/master/entrybuffer.pl

What docs are you reading? I can't find any perl specific docs to suggest you can pass a reference