Ok, this has bothered me since the Impulse Tracker days - IT was the first tracker i used that could have patterns of different lengths.
What happens is, let’s say most of your patterns are 128 rows in length, but you have a few of them that are shorter, say 32 or 64 in length. When you select a range of tracks or columns of the entire pattern length (128 rows) and try to copy/paste stuff in all patterns, as soon as you hit that shorter pattern, your selection just got truncated to that pattern’s length, so you end up copying + pasting only HALF of the remaining patterns - except YOU DON’T SEE THIS ON SCREEN, because normally your cursor will be at the top of the pattern.
…so, feature request: when switching to a pattern whose length is shorter than the selection, “remember” the height/length of the current selection and try to restore it when switching back to another (longer) pattern.
The workaround i use most of the time is, to have all the patterns of the same length, but when i do need to insert a shorter pattern, instead of changing the pattern’s length i just insert a pattern break command. Anyway, hope some of that made sense.