I used that example here
There you can see line numbers, for all location tags. I do not want to use linenumbers, since they might change from time to time.
When I open the *.ts file in the Linguist, the *.ui is shown there as well, as you can see here:
The green area is the UI Widget displayed in the Linguist (actually the same view as in the QtCreator Designer).
With that line numbers it is working. Without, not, Why? I do not want to maintenance line numbers in translation files.
(Similar questions: handling ampersands https://stackoverflow.com/questions/33422473/qtranslator-with-linguist-file-not-translatable)