[dwm] xinerama idx patch

[pancake]

I have found in the xinerama source that the screen index is hardcoded
to 0. I think this should use a define in config.h to choose which is
the selected xinerama screen you want to use as 'main'.

Here's the patch:

config.def.h:

#define XINERAMA_IDX 0

dwm.c:

void
updategeom(void) {
#ifdef XINERAMA
        int i;
        XineramaScreenInfo *info = NULL;

        /* window area geometry */
        if(XineramaIsActive(dpy)) {
                info = XineramaQueryScreens(dpy, &i);
                wx = info[XINERAMA_IDX].x_org;
                wy = showbar && topbar ? info[XINERAMA_IDX].y_org + bh :
info[XINERAMA_IDX].y_org;
                ww = info[XINERAMA_IDX].width;
                wh = showbar ? info[XINERAMA_IDX].height - bh :
info[XINERAMA_IDX].height;
                XFree(info);
        }
        else
#endif



I use XINERAMA_IDX=1 (because i prefer my right screen than left one)

PD: I think that expanding the master and slave area on more than one
screen is anoying. I would prefer to have a single screen with another
external one for floating windows.