在X11上激活一个窗口，为什么我会丢失标题栏？

Question

Using the bellow code, I am activating a window on X11.

I'm using FindWindow to get the window handle, which works just fine. Then I want to bring the specified window in the foreground. To do this, I use XRaiseWindow.

XRaiseWindow(display, wdThisWindow);

However, XRaiseWindow doesn't work on some windows (quite many, but not all). I figured this is because their override_redirect WindowAttribute is not set to true. So I used XChangeWindowAttributes to set this property to true. Now, XRaiseWindow brings all windows to the top. The problem is, EyeOfGnome (picture viewer) and all other applications looses the top title bar... (you know, the one with the close control on the right...). And what's even worse, the window doesn't go to the background anymore...

I figured if I set back the override_redirect property after I raised the window, the problem would be gone. But... The problem is now gone from all applications (such as gnome-terminal) - all except EyeOfGnome (Picture Viewer)...

Am I missing something, or is this an EyeOfGnome issue, or is it a general GTK issue ?

Here's the problem-causing part of the code:

XSetWindowAttributes xswa;
xswa.override_redirect = True;
XChangeWindowAttributes(display, wdThisWindow, CWOverrideRedirect, &xswa);
XRaiseWindow(display, wdThisWindow);
xswa.override_redirect = False;
XChangeWindowAttributes(display, wdThisWindow, CWOverrideRedirect, &xswa);
XSetInputFocus(display, wdThisWindow, RevertToNone, CurrentTime);

And this is the complete code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <X11/X.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xatom.h>



// Info: xwininfo
// I am compiling using 
// gcc -o activate activate.c -L/usr/X11R6/lib -lX11


// ERROR HANDLER, GENERIC
static int ErrorHandler (Display *display, XErrorEvent *error)
{
   //printf ("\r\n error! \r\n");// gcc -o xwinspy lol.c -L/usr/X11R6/lib -lX11
   return 0;
}
// END ERROR HANDLER


// Recursively search through all windows on display
Window SearchWindow(char* szWindowToFind, int level, Display *display, Window rootWindow, int iMatchMode, int showErrors)
{
    Window parent;
    Window *children;
    unsigned int noOfChildren;
    int status;
    int i;
    Window wSearchedWindow = 0;

    char* win_name;
    if (XFetchName(display, rootWindow, &win_name))
    {
            //printf("WinName (Level %d): %s\n", level, win_name);
            if(iMatchMode == 0)
            {
                if( strstr(win_name, szWindowToFind) )
                {
                    return rootWindow;
                }
            }
            else if(iMatchMode == 1)
            {
                if( !strcmp(win_name, szWindowToFind) )
                {
                    return rootWindow;
                }
            }
            else if(iMatchMode == 2)
            {
                if( strcasestr(win_name, szWindowToFind) )
                {
                    return rootWindow;
                }
            }
            else if(iMatchMode == 3)
            {
                if( !strcasecmp(win_name, szWindowToFind) )
                {
                    return rootWindow;
                }
            }
            else 
            {
                if( strstr(win_name, szWindowToFind) )
                {
                    return rootWindow;
                }
            }

    } // End if XFetchName



    status = XQueryTree (display, rootWindow, &rootWindow, &parent, &children, &noOfChildren);

    if (status == 0)
    {
        if (showErrors)
            printf ("ERROR - Could not query the window tree. Aborting.\r\n");
        return;
    }

    if (noOfChildren > 0)
    {
        for (i=0; i < noOfChildren; i++)
        {
            wSearchedWindow = SearchWindow(szWindowToFind, level+1, display, children[i], iMatchMode, showErrors);
            if(wSearchedWindow)
            {
                break;
            }
        }
    } 

    XFree ((char*) children);

    return wSearchedWindow;
} // End Sub EnumerateWindows


Window FindWindow(char* szWindowToFind)
{
    Display *display = XOpenDisplay (NULL);
    int screen = DefaultScreen (display);

    XSetErrorHandler(ErrorHandler);

    Window rootWindow = RootWindow (display, screen);   

    Window wSearchedWindow = SearchWindow(szWindowToFind, 0, display, rootWindow, 0, 0);

    char* win_name;
    if (XFetchName(display, wSearchedWindow, &win_name))
    {
        printf("Found: %s\n", win_name);
    }

    XCloseDisplay (display);
    return wSearchedWindow;
}

void ActivateWindow(char* szWindow)
{
    Window wdThisWindow = FindWindow(szWindow);

    Display *display = XOpenDisplay (NULL);

    char* win_name;
    if (XFetchName(display, wdThisWindow, &win_name))
    {
        printf("Activating: %s\n", win_name);
    }

    XSetErrorHandler(ErrorHandler);

    XSetWindowAttributes xswa;
    xswa.override_redirect = True;
    XChangeWindowAttributes(display, wdThisWindow, CWOverrideRedirect, &xswa);
    XRaiseWindow(display, wdThisWindow);
    xswa.override_redirect = False;
    XChangeWindowAttributes(display, wdThisWindow, CWOverrideRedirect, &xswa);
    XSetInputFocus(display, wdThisWindow, RevertToNone, CurrentTime);

    XCloseDisplay (display);
}



// ENUMARATE THROUGH WINDOWS AND DISPLAY THEIR TITLES
void EnumerateWindows(int level, Display *display, Window rootWindow, int showErrors)
{
    Window parent;
    Window *children;
    unsigned int noOfChildren;
    int status;
    int i;

    char* win_name;
    if (XFetchName(display, rootWindow, &win_name))
    {
            printf("Window-Name (Level %d): %s\n", level, win_name);
    }

    status = XQueryTree (display, rootWindow, &rootWindow, &parent, &children, &noOfChildren);

    if (status == 0)
    {
        if (showErrors)
            printf ("ERROR - Could not query the window tree. Aborting.\r\n");
        return;
    }

    if (noOfChildren > 0)
    {
        for (i=0; i < noOfChildren; i++)
        {
            EnumerateWindows(level+1, display, children[i], showErrors);
        }
    } 

    XFree ((char*) children);
} // End Sub EnumerateWindows


void ListAllWindowsOnScreen()
{
    Display *display = XOpenDisplay (NULL);
    int screen = DefaultScreen (display);

    XSetErrorHandler(ErrorHandler);

    Window rootWindow = RootWindow (display, screen);   

    EnumerateWindows(0, display, rootWindow, 0);
    XCloseDisplay (display);
}


int main(int argc, char *argv[])
{
    ListAllWindowsOnScreen();
    //ActivateWindow("000727");
    return EXIT_SUCCESS;
}

Answer 1

What you have to do, as ninjalj mentions, is use the protocols in the EWMH specification rather than making these raw X protocol requests. What you're doing here will confuse the heck out of both GTK+ and the window manager.

Specifically, what you want to do here is send a _NET_ACTIVE_WINDOW client message, with the source indication (http://standards.freedesktop.org/wm-spec/wm-spec-1.4.html#sourceindication) probably set to say you're a pager.

Incidentally there's a library called libwnck (which I wrote originally but other people now maintain) which will do all this for you. Even if you don't use it, you can look at its source code to learn how to do stuff.

Answer 2

OverrideRedirect is for windows that bypass the window manager. The protocol for requesting stacking order changes is described in the ICCCM , section 4.1.5. The EWMH spec includes some extensions to this protocol, like layered stacking order and window activation (giving focus and possibly raising the window).