Resizing columns are somehow possible by dragging the borders between the data cells, in addition to headers.
This becomes problemmatic when the “drag” option is enabled :
http://snippet.webix.io/d687e097
I think resizing columns should be limited to header cells area.
Yep, good catch
We will update code in the next build, when drag-n-drop enabled, resizing in data area will be blocked.
maksim, thank you!
I’m testing/studying the webix a for a couple weeks and found it absolutely better (and much faster!) then any other.
Thank you for creating such an excellent library.
I will keep posting suggestions and bug reports to help improving it, is this place the best for posting bug reports o shall I use github?
is this place the best for posting bug reports o shall I use github?
You can use forum or tracker, as you wish.
Tracker may be a bit better, because a status of an issue is more clear. Also, we will not forget to fix such issue for sure 
drag:true also breaks column dragging :
http://snippet.webix.io/5a1dea86
New build will be available on Monday, will fix the above issue as well