Instead of hijacking another thread, i’ve made a new topic here:
I’ve thought one could use the length of the sample, when played at the basenote. Surely Renoise knows how long a pattern is and it could simply map that over the sample.
Another idea would be to have fixed size selections, one can move around like a block, a dropdown list or a simple textfield for entering the step width would be enough. Imagine it a bit like fixed size masks in a graphic program, like 100px * 60px.