It is a bit more cumbersome to write, but the problem is that I don't know how to exit from the overlined part once I use this accent, so when I want to enter this product (again, in this example, the line over the first X is, to my eyes, a bit too small)

using \overline, I tried this :

typing \overline then Enter, then X then right arrow to exit the overline environment (hopefully) then ^, then T (looks fine so far) then right arrow again to exit the exponent, and then the line extends over the exponent too, and I can't exit the overline, even after exiting the formula itself (which looks like a bug to me)

It is even worse in a demo environment where if I do the same thing, that is, in a formula, \overline enter X right arrow then I get this with the line extending to the right margin :

So the first question is : how would I manage the kind of result I'd like ? 

And the second would be : Am I right that \overline is kind of buggy with TeXmacs right now ?

And if it is not a bug, how would one properly use the hybrid latex command \overline ?

Hopefully the images I pasted in this mail will show properly. I remember last time Joris told me they didn't, so I tried to compose this mail using gmail web client.