Actually EWMH _NET_CURRENT_DESKTOP gives you which is the current desktop for X, not relative to the application. Here's a C snippet to get the _WM_DESKTOP of an application. If run from the KDE Konsole in question it will give you what desktop it is on, even it is not the active desktop or not in focus.
#include <X11/Xlib.h>
#include <X11/Shell.h>
...
Atom net_wm_desktop = 0;
long desktop;
Status ret;
/* see if we've got a desktop atom */
Atom net_wm_desktop = XInternAtom( display, "_NET_WM_DESKTOP", False);
if( net_wm_desktop == None ) {
return;
}
/* find out what desktop we're currently on */
if ( XGetWindowProperty(display, window, net_wm_desktop, 0, 1,
False, XA_CARDINAL, (Atom *) &type_ret, &fmt_ret,
&nitems_ret, &bytes_after_ret,
(unsigned char**)&data) != Success || data == NULL
) {
fprintf(stderr, "XGetWindowProperty() failed");
if ( data == NULL ) {
fprintf(stderr, "No data returned from XGetWindowProperty()" );
}
return;
}
desktop = *data;
XFree(data);
and desktop should be the index of the virtual desktop the Konsole is currently in. That is not the same which head of a multi-headed display. If you want to determine which head, you need to use XineramaQueryScreens (Xinerama extension, not sure if there is a XRandR equivalent or not. Does not work for nVidia's TwinView.
Here's an excerpt from some code I wrote, that given a x and y, calculate the screen boundaries (sx, sy, and sw with screen width and sh for screen height). You can easily adapt it to simply return which "screen" or head x and y are on. (Screen has a special meaning in X11).
#include <X11/X.h>
#include <X11/extensions/Xinerama.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
Bool xy2bounds(Display* d,int x, int y, int* sx, int* sy, int* sw, int* sh) {
*sx = *sy = *sw = *sh = -1; /* Set to invalid, for error condition */
XineramaScreenInfo *XinInfo;
int xin_screens = -1;
int i;
int x_origin, y_origin, width, height;
Bool found = False;
if ( d == NULL )
return False;
if ( (x < 0) || (y < 0) )
return False;
if ( True == XineramaIsActive(d) ) {
XinInfo = XineramaQueryScreens( d, &xin_screens );
if ( (NULL == XinInfo) || (0 == xin_screens) ) {
return False;
}
} else {
/* Xinerama is not active, so return usual width/height values */
*sx = 0;
*sy = 0;
*sw = DisplayWidth( d, XDefaultScreen(d) );
*sh = DisplayHeight( d, XDefaultScreen(d) );
return True;
}
for ( i = 0; i < xin_screens; i++ ) {
x_origin = XinInfo[i].x_org;
y_origin = XinInfo[i].y_org;
width = XinInfo[i].width;
height = XinInfo[i].height;
printf("Screens: (%d) %dx%d - %dx%d\n", i,
x_origin, y_origin, width, height );
if ( (x >= x_origin) && (y >= y_origin) ) {
if ( (x <= x_origin+width) && (y <= y_origin+height) ) {
printf("Found Screen[%d] %dx%d - %dx%d\n",
i, x_origin, y_origin, width, height );
*sx = x_origin;
*sy = y_origin;
*sw = width;
*sh = height;
found = True;
break;
}
}
}
assert( found == True );
return found;
}