[bug]? extent something from customize

Recent keystrokes: ( C-e space . space 9 9 9 ) down down down down down down down down right right right right right right right right right right ( c o n s space ( C-e C-j ( i n M-/ ) up left space : t a g space " F r o m " down left space : t a g space " T o " C-e ) ) button1 button1up backspace backspace up up up up up C-x C-s button3 misc-user C-M-x button1 button1up ' C-M-x C-x C-s button3 misc-user misc-user k button1 button1up button1 button1up f1 l Recent minibuffer messages (most recent first): extent doesn't belong to a buffer or string: #<extent (detached)* I help-echo balloon-help keymap glyph-widget 0x8f0c3e8 from no buffer> k not defined.