Hi, I have some additional information which may help resolve the "small white rectangle" issue reported in Small white rectangle appearing on upper left side of RStudio, what the heck!!?? - #8 by andresrcs
I made this gremlin go away by closing the edit window in which it had been a minor visual annoyance for dozens of RStudio sessions. When I reopened the file for editing, hey presto, the gremlin had disappeared.
My best-guess as to the origins of this gremlin is that it is a dysfunctional remnant of an affordance for the spell-corrector. In the screenshots below: a wavy red underline indicates a word that is not found in the spell-corrector's dictionary. Somewhat surprisingly, the spell-corrector's GUI affordance is not found by clicking on the underline, nor by mouse-hovering on the underlined word. At least not on my Win11 installation. YMMV.
Before I write anything more about this very minor but annoying GUI defect I want to say
"Thank you, thank you, thank you, mille grazie to the RStudio GUI team!!! Well done!"
Returning to my partial-localisation of this gremlin: a left-click on the small-box that's displayed somewhat below and to the right of the wavy underline will sometimes (but not always) reveal affordances for spell-correction options such as "Add to user dictionary".
(As a newbie to this community I'm not allowed to include multiple screenshots or links in a posting. However you'll find my other screenshots by googling on "how-to-remove-a-small-box-at-the-bottom-of-my-coding-window-in-r", as that'll lead you to a stack-overflow discussion in which I have posted my images and analysis)
The small-box will sometimes (but not always) remain at a fixed location within the edit-display-window when the underlying text is scrolled -- and it may continue to appear even after the wavy-underlined word is no longer visible.
Editing the text when the small-box is displayed may convert it into a dysfunctional gremlin. I'm unable to reproduce this behaviour but I'm pretty sure the gremlin-creation process is associated, somehow, to edits in which the wavy-underlined word has been deleted or modified.
OK, I've already had more than enough "fun" in the "game" of localising this gremlin! Perhaps someone in the RStudio community would like to take over... at least to verify that the gremlin is reliably "slain" by the simple expedient of closing the edit-window in which it is "living"? In my experience: it will survive dozens of closures and reopens of RStudio sessions, i.e. is in a "dormant" state in the serialised form of the edit-window that is preserved across sessions. (Having such a persistent edit-window is a very very nice feature of RStudio ... so thank you again, grazie ancora, RStudio GUI team! 