I’m using: SWI-Prolog version 10
I want the code to: display with XPCE a bubble help message text in a specific TTF font.
But what I’m getting is: the same default TTF font.
My code looks like this: (just the standard XPCE code)
% your code here
As is, that is not provided. See library(help_message). You’d have to rewrite that a little. The font is hard wired to be normal when creating the single window instance.
Thank you very much for your response.
Was it difficult to implement or is it just meant to keep things as simple as possible?
XPCE is a fantastic tool ; the continued addition of such improved functionalities will contribute to the already excellent reputation of SWI-Prolog.
To be consistent with these words, I will make my own little contribution towards that effort.
Rich help-messages with multiple fonts, styles and even special effects (postscript, susbcript, …) are very handy in language-intensive and specialised applications.
To what extent can we, the users, adapt the source code? Or, should we expect the upgrades from your side, so that the benefits are to all users (the preferred option)?
Its open source 
If you improve something, make a PR and it will typically be merged. Surely small clean patches that are a clear improvement. Long complicated changes are judged on usefulness size and maintainability. The idea is to accept changes … unless.
So, start swipl and type
?- edit(library(help_message)).
The thing is basically a window that displays a label. You can change that do show a more general object. There are several options, Possibly the content of the message can be allowed to be a string or an arbitrary graphical?
That is very clear. Thanks.