cantthinkofanickname wrote:
> I can't see an option for attaching a picture
Upload your screen shot to one of the many image sharing
sites, and post a link to it.

Which window manager / desktop environment are you using?
Do you use open source driver or binary driver?
Is this your only Linux setup or can you try it on
other computers with different hw/sw combinations
(other graphics cards, versions of Linux)?

Best regards,

Dušan Peterc
http://www.arahne.si

Some window snippets can be found at <http://img02.picoodle.com/img/
img02/6/10/22/f_uploadm_7b8d968.png>

> Which window manager / desktop environment are you using?

This a legacy Air Traffic Control system. There doesn't appear to be a
desktop environment (nothing like KDE, GNOME, etc.)

> Do you use open source driver or binary driver?

Vendor driver. More details:
Matrox ATC: Summit_FX-Silver-MATROX-ATC--XB-2.4-9h (custom
driver from XiG)
XServer: /usr/X11R6/bin/Xaccel [2.4.0 (build 17) 3D Accelerated-X (tm)
Display Server]

> Is this your only Linux setup or can you try it on
> other computers with different hw/sw combinations
> (other graphics cards, versions of Linux)?

As mentioned in the email, there is the class B machine that works
fine.
These have the following video card:

01:00.0 VGA compatible controller: nVidia Corporation NV44 [Quadro NVS
285] (rev a1)

I'm told that apart from the video card Class-A and Class-B machines
are identical.
It's not looking good for the video card.

However, this appears to be a relatively new problem. I don't know
what's changed
to cause this.

Thanks,
Jevon

Test

I have been digging through the application code. This is not a
standard problem. The application implements its own window manager
(it does not use the Motif manager like I thought) and handles *all*
the window events. The problem will probably be here and related to
video card in some way. I think I'm on my own.

Thanks,
Jevon.

cantthinkofanickname wrote:
> I have been digging through the application code. This is not a
> standard problem. The application implements its own window manager
> (it does not use the Motif manager like I thought) and handles *all*
> the window events. The problem will probably be here and related to
> video card in some way. I think I'm on my own.

Yes, with a custom set-up like this, you really are.

I can only give you one example of visual bug I am experiencing.
On Linux, with nvidia cards, and nv open source driver,
the GXinvert drawing mode is not implemented correctly.
As I use invert for rubber bands and other quick feedback,
it sometimes leaves garbage on the screen.
The problem goes away if I install the non-open source binary
nvidia driver.

Good luck with bug hunting.

Dušan Peterc
http://www.arahne.si

This is like what I'm seeing. The rubberband (rectangle) is drawn
during the move operation. On the move finalize operation the
rubberband is undrawn (XOR the rectangle). Here's the interesting bit.
When I step through these operations in gdb it works fine; however, if
I 'continue' through these operations then garbage is left behind.
What you say is very helpful.

Thanks,
Jevon

cantthinkofanickname wrote:
> This is like what I'm seeing. The rubberband (rectangle) is drawn
> during the move operation. On the move finalize operation the
> rubberband is undrawn (XOR the rectangle). Here's the interesting bit.
> When I step through these operations in gdb it works fine; however, if
> I 'continue' through these operations then garbage is left behind.

For these kind of XOR feedback to work correctly,
it is quite important that your drawing area is not modified
while the operation is going on.

One possible scenario:
1. start operation, xor the marked area
2. an expose event, area is partially redrawn
3. end operation, xor the marked area, garbage left behind.

Alternatively, instead of expose, window manager could use
backing store for transient windows (like menu),
no event would be sent to your app,
but results could be similar.

As today's graphics cards and CPU are several orders of
magnitude faster, it is quite feasible to drop the xor,
and use a feedback method which permit double or partial
redraws without anomalies.

Best regards,

Dušan Peterc
http://www.arahne.si

The scenario you describe is actually described in
a comment by a previous developer. It was handled
by a partial refresh of the window. The garbage I
am seeing though seems to be something a little
different.

They (the developers) have really made a mess of
this. The rubber-band code is insidious and pops
up every where: any place where there is some kind
of change in the window (cut+paste too).

I'm about to give up. Like you say, I'll probably just
force a refresh of the entire window.

Thanks again for your help.
Jevon

Fixed!

I lucked out. Actually, you gave me a clue.

I made a guess and inserted an XSync()
before the undraw. This fixed it. There must
be some old X events floating around that
interefere with the undraw; and specific to
this kind of XServer.

Hopefully I never have to look at this part of
the code again.

Thanks very much,
Jevon