Is _NET_FRAME_EXTENTS must be set?

["Oleg Sukhodolsky" <son two gmail com>]

Hi,

the part of the spec about _NET_FRAME_EXTENTS is unclear for me :(

In _NET_REQUEST_FRAME_EXTENTS specs says "To retrieve such an estimate, the
Client MUST send a _NET_REQUEST_FRAME_EXTENTS message to the root
window. he Window Manager MUST respond by estimating the prospective
frame extents and setting the
window's _NET_FRAME_EXTENTS property accordingly."

So, it looks like I (as a client) have to sent
_NET_REQUEST_FRAME_EXTENTS to get
correct extents in _NET_FRAME_EXTENTS.

> From the other hand in paragrath about _NET_FRAME_EXTENTS the spec says:
"The Window Manager MUST set _NET_FRAME_EXTENTS to the extents of the window's
frame. left, right, top and bottom are widths of the respective
borders added by the Window
Manager."

So, does this means that _NET_FRAME_EXTENTS must be sat anyway?  If
yes, then when
I can be sure that values in _NET_FRAME_EXTENTS are correct?

Thanks in advance, Oleg.