Iv'e been longing for this feature ever since I started to use LMMS in 2015. I make single-note instrument samples from existing tracks all the time for my projects and I've always hated how the sample speeds up / slows down when moving up or down the keyboard. How difficult would it be to fix this issue / are there any plans to address this issue?
Just for information
This is called pitch shifting (pitch change without altering the playback speed).
The complementary function is called time stretching (changing the playback speed without altering the pitch).
There are pitch shift effects in LMMS. With these effects, the pitch changes have to be controlled via automations or LFO.