How to make text in rendered PDF pages selectable?

[Радомир Хаџић <radomirhadzic46 gmail com>]

Hello.

I'm using Poppler to render PDF page onto GtkDrawingArea surface.
Everything renders correctly so far, but I can't figure out how to
make text selectable. For example, a user may wish to select some text
using mouse with the intention of copying it, or when user searches a
document for a string it would be practical to make that text stand
out by selecting it.

All I'm asking for is some guidance and/or brief explanation how am I
supposed to achieve that, since I cannot find anything online or in
the documentation.