[comp.windows.x] why twm gets "sequence lost"

RWS@ZERMATT.LCS.MIT.EDU (Robert Scheifler) (06/08/88)

The Xlib manual, section 8.12.2, under XSetErrorHandler sez:
    "However, the error handler should not perform any operations
    (directly or indirectly) on the display."
twm violates this, breaking internal Xlib invariants.

mss+@ANDREW.CMU.EDU (Mark Steven Sherman) (06/08/88)

From xpert:

> "From: Robert Scheifler <RWS@zermatt.lcs.mit.edu>
> Subject: why twm gets "sequence lost"

> The Xlib manual, section 8.12.2, under XSetErrorHandler sez:
>     "However, the error handler should not perform any operations
>     (directly or indirectly) on the display."
> twm violates this, breaking internal Xlib invariants."

I have seen bug reports coming back to us that ATK gets "sequence lost" errors
from Xlib. Technically, the error handler in ATK also violates the above
requirement, because it calls XGetErrorText, as per same section (in my version
of the manual):

> "It is recommended that XError [I assume this means the error handler, since
> XError is an event, not a routine] use XGetErrorText for obtaining textual
> descriptions of the specified error code. The definition for this function is

> XGetErrorText(*display*, code, bufer_return, length)"
Could ATK be getting strange behavior because it is trying to print an error
message from the error handler?

                -Mark