Re: [XForms] RE: xforms & dual screen

[Jens Thoms Toerring]

Hi Nick and Jens,

On Tue, May 18, 2010 at 12:30:32PM +0200, nick Nieuwkoop wrote:
> We have an application that runs with XForms. When we
> add or remove lines of code that should be controlling the xServer, nothing
> happens. From this we figured out that xForms is ‘controlling’ the xServer.

I don't know what you mean with "controling the X server" but the
XForms library is basically just a wrapper around the Xlib library.
And thus programs using this library can't 'control' the X server
but can only send requests to the X server and listen for replies.
So could you be a bit more specifiec about the lines "that should
be controlling the xServer"?

> Besides this application we have been able to show in standard Xwindows
> forms “hello world” in two different size windows, one on the first screen
> and the other one on the second screen. This uses the xServer library
> directly. So we know the configurations are correct. Also this confirms that
> it is definitely possible to use both screens.

Of course, there must be a way to send windows to two screens
(oherwise having a second screen wouldn't make much sense;-).
What do you do in this program (or when starting it) to control
which screen the window is shown on? As I said in my previous
mail I never have used a dual-screen setup so you need to help
me a bit here. And can you also display one window on the one
screen and another one on the other screen with such a program?
I would be interested to see how this gets done.

> Also the current application has used threads before, where one thread
> handles the input of the buttons from xForms(the callbacks), while the other
> thread controls the other forms shown on the screen. Would it be possible to
> use a thread for each screen, maybe even for each form or will this have no
> effect on the use of the screens.

XForms is not thread-safe. It was written long before threads
were available on UNIX (or before Xlib itself became thread-safe
when, as far as I understand it, XInitThreads() is called at the
very start), so if you have gotten away with using threads with
an XForms program then it probably was more die to luck then to
XForms design.
                            Best regards, Jens
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