ModifyLayerFrames(id, frames[, pos])
frames, then the anim layer is extended by this number of frames. If you specify a negative value, the number of frames specified are removed from the anim layer.
The optional argument
pos can be used to specify where the new
frames shall be inserted or from where the frames shall be removed,
respectively. If you do not specify the optional argument or set
it to 0, frames are added at the end of the anim layer or removed from
the end of the anim layer, respectively.
This command works only with anim layers that have their frames buffered entirely in memory. You cannot use it for anim layers that load their frames dynamically from disk.
ModifyLayerFrames(1, -5, 1)The code above removes the first five frames from anim layer number 1.