Xlib and Firefox behavior

Question

I'm trying to create a small window manager (just for fun), but I'm having problems in handling windows created by Firefox (only with that application, other apps works fine)

The problem is, after I launch Firefox, and add my decoration, it seems to work fine, but if for example I try to click on the menu button, the (sub)window doesn't appear.

What seems to happen is that after the click, a ClientMessage event is fired with the following values:

Data: (null)
Data: _NET_WM_STATE_HIDDEN
Data: (null)
Data: (null)
Data: (null)

Now the problem is that I don't know how to show the window, which window. I tried with:

• XRaiseWindow
• XMapWindow
• I tried to get the transient window and show it

But without success. What I don't understand is that if this client message is generated by the menu subwindow or not.

How should I show a window that is in _NET_WM_STATE_HIDDEN?

Another strange problem is that after receiving the ClientMessage, I always receive 2 UnMapNotify Events.

I also have another question, if I want to show the "File, Edit" menù (in Firefox it appears, if I remember correctly, when you press the Alt button.

Maybe Firefox creates a tree of windows?

This is the loop where I handle the events:

while(1){
    XNextEvent(display, &local_event);
    switch(local_event.type){
        case ConfigureNotify:
            configure_notify_handler(local_event, display);
        break;
        case MotionNotify:
            motion_handler(local_event, display);
        break;
        case CreateNotify:
            cur_win = local_event.xcreatewindow.window;
            char *window_name;
            XFetchName(display, cur_win, &window_name);
            printf("Window name: %s\n", window_name);
            if(window_name!=NULL){
                if(!strcmp(window_name, "Parent")){
                    printf("Adding borders\n");
                    XSetWindowBorderWidth(display, cur_win, BORDER_WIDTH);
                }
                XFree(window_name);
            }
        break;
        case MapNotify:
            map_notify_handler(local_event,display, infos);
        break;
        case UnmapNotify: 
            printf("UnMapNotify\n");
        break;
        case DestroyNotify:
            printf("Destroy Event\n");
            destroy_notify_handler(local_event,display);
        break;
        case ButtonPress:
            printf("Event button pressed\n");
            button_handler(local_event, display, infos);
        break;
        case KeyPress:
            printf("Keyboard key pressed\n");
            keyboard_handler(local_event, display);
        break;
        case ClientMessage:
            printf("------------ClientMessage\n");
            printf("\tMessage: %s\n", XGetAtomName(display,local_event.xclient.message_type));
            printf("\tFormat: %d\n", local_event.xclient.format); 
            Atom *atoms = (Atom *)local_event.xclient.data.l;
            int i =0;
            for(i=0; i<=5; i++){
                printf("\t\tData %d: %s\n", i, XGetAtomName(display, atoms[i]));
            }
            int nchild;
            Window *child_windows;
            Window parent_window;
            Window root_window;
            XQueryTree(display, local_event.xclient.window, &root_window, &parent_window, &child_windows, &nchild);
            printf("\tNumber of childs: %d\n", nchild);
        break;
    }

Now in the clientmessage actually I'm just trying to see collect some information to understand what is happening. And what I can see from the code above, is that the window that raised the event contains one child (again: is that the menu? or not?)

The code for the MapNotify event, where I add the decoration is the following:

void map_notify_handler(XEvent local_event, Display* display, ScreenInfos infos){
    printf("----------Map Notify\n");
    XWindowAttributes win_attr;
    char *child_name;
    XGetWindowAttributes(display, local_event.xmap.window, &win_attr);
    XFetchName(display, local_event.xmap.window, &child_name);
    printf("\tAttributes: W: %d - H: %d - Name: %s - ID %lu\n", win_attr.width, win_attr.height, child_name, local_event.xmap.window);
    Window trans = None;    
    XGetTransientForHint(display, local_event.xmap.window, &trans); 
    printf("\tIs transient: %ld\n", trans);
    if(child_name!=NULL){
      if(strcmp(child_name, "Parent") && local_event.xmap.override_redirect == False){
        Window new_win = draw_window_with_name(display, RootWindow(display, infos.screen_num), "Parent", infos.screen_num, 
                           win_attr.x, win_attr.y, win_attr.width, win_attr.height+DECORATION_HEIGHT, 0, 
                           BlackPixel(display, infos.screen_num));
        XMapWindow(display, new_win);
        XReparentWindow(display,local_event.xmap.window, new_win,0, DECORATION_HEIGHT);
        set_window_item(local_event.xmap.window, new_win);
        XSelectInput(display, local_event.xmap.window, StructureNotifyMask);
        printf("\tParent window id: %lu\n", new_win);
        put_text(display, new_win, child_name, "9x15", 10, 10, BlackPixel(display,infos.screen_num), WhitePixel(display, infos.screen_num));
      }
    }
    XFree(child_name);
}

Now can someone help me with these problems? Unfortunately I already googled many times, but without success.

To sum up, my issues are two: 1. How to show subwindows from Firefox 2. How to show the File, Edit menu.

UPDATE

I noticed something strange testing Firefox with xev to understand what events are fired in order to show an application. I saw that using Firefox in unity, and using Firefox in another window manger, the events fired are completely different. In Unity I have only:

1. ClientMessage
2. UnmapNotify

Instead using Firefox, for example with xfce4, the xevents generated are more:

1. VisiblityNotify (more than one)
2. Expose event (more than one)

But if I try to enable VisibilityChangeMask in my wm, I receive the following events:

• ConfigureNotify
• ClientMessage
• MapNotify
• 2 UnMapNotify

UPDATE 2

I tried to read the XWMhints properties in the ClientMessage window (probably the menù window) and the values are:

• For the flags 67 = InputHint, StateHint, WIndowGroupHint

• For the initial state NormalState

UPDATE 3

I tried to look how another window manager works, and I was looking at the source code of calmwm. What is my understanding is that, when the ClientMessage event arrives, with a _NET_WM_STATE message, it updates these properties, and in the case of _NET_WM_STATE_HIDDEN it clears this property, and the result will be that the property will be deleted. So I tried to update my code to delete that property, but it's still not working. Anyway the relevant updated code in client_message_handler now looks like this:

Atom *atoms = (Atom *)local_event.xclient.data.l;
int i =0;
for(i=0; i<=5; i++){
    printf("\t\tData %d: %s\n", i, XGetAtomName(display, atoms[i]));
    if(i==1){
        printf("\t Deleting Property: _NET_WM_STATE_HIDDEN \n");
        XDeleteProperty(display, cur_window, atoms[i]);
    }
}

It is only a test, and I'm sure that i=1 in my case is the _NET_WM_STATE_HIDDEN property.

Here a link to calmwm source code: https://github.com/chneukirchen/cwm/blob/linux/xevents.c

So I'm still stuck at that point.

UPDATE 4

Really I don't know if it helps, but I tried to read the window attributes in the MapNotify Event, and the window map_state is IsViewable (2).

UPDATE 5

I found a similar problem here in SO, using xlib with python: Xlib python: cannot map firefox menus

The solution suggests to use XSetInputFocus, i tried that on my XMapNotify handler:

XSetInputFocus(display, local_event.xmap.window, RevertToParent, CurrentTime);

But it still doesn't help, the firefox menu still doesn't appear!! And i have the same problem with right-click.

UPDATE 6

Playing with xconfigurenotify event and unmap event i found that the: Xconfigure request has 2 window fields: window and above, and when the the xconfigurerequest.window value is the same of xunmap.window value.

And also that the xconfigurerequest.above is always changing, but xconfigurerequest.window is always the same in all events.

It seems that the xconfigurerequest.above is related to what menu i'm trying to open. For example:

• if right-click on a page i get an id (always the same for every subsequent click)
• if i right-clik on a tab, the above value is another one
• and the same happen if i left-click the firefox main menu

Still don't know if that helps.

Really don't know Anyone got any idea?

Answer 1

This question is ancient but for the benefit of anyone who stumbles across it looking for an answer to this, here's an edited (chopped to bits) sample of how I solved this based on the hints above:

while (event = xcb_poll_for_event(connection)) {
    uint8_t actual_event = event->response_type & 127;
    switch (actual_event) {
        case XCB_MAP_NOTIFY: ;
            xcb_map_notify_event_t *map_evt = (xcb_map_notify_event_t *)event;
            if (map_evt->override_redirect) {
                xcb_get_property_cookie_t cookie = xcb_icccm_get_wm_transient_for(connection, map_evt->window);
                xcb_window_t transient_for = 0;
                xcb_icccm_get_wm_transient_for_reply(connection, cookie, &transient_for, NULL);
                if (transient_for) {
                    xcb_set_input_focus(connection, XCB_INPUT_FOCUS_POINTER_ROOT, transient_for, XCB_CURRENT_TIME);
                }
                xcb_flush(connection);
            }
            break;
        case XCB_CLIENT_MESSAGE: ;
            xcb_client_message_event_t *message_evt = (xcb_client_message_event_t *)event;
            xcb_get_atom_name_cookie_t name_cookie = xcb_get_atom_name(connection, message_evt->type);
            xcb_get_atom_name_reply_t *name_reply = xcb_get_atom_name_reply(connection, name_cookie, NULL);
            int length = xcb_get_atom_name_name_length(name_reply);
            char *atom_name = malloc(length + 1);
            strncpy(atom_name, xcb_get_atom_name_name(name_reply), length);
            atom_name[length] = '\0';
            free(atom_name);
            free(name_reply);

            if (message_evt->type == ewmh->_NET_WM_STATE) {
                xcb_atom_t atom = message_evt->data.data32[1];
                unsigned int action = message_evt->data.data32[0];
                xcb_get_atom_name_cookie_t name_cookie = xcb_get_atom_name(connection, atom);
                xcb_get_atom_name_reply_t *name_reply = xcb_get_atom_name_reply(connection, name_cookie, NULL);
                int length = xcb_get_atom_name_name_length(name_reply);
                char *atom_name = malloc(length + 1);
                strncpy(atom_name, xcb_get_atom_name_name(name_reply), length);
                atom_name[length] = '\0';
                if (action == XCB_EWMH_WM_STATE_REMOVE) {
                    if (atom == ewmh->_NET_WM_STATE_HIDDEN) {
                        xcb_delete_property(connection, message_evt->window, ewmh->_NET_WM_STATE_HIDDEN);
                    }
                }
                free(atom_name);
                free(name_reply);
            }
            break;
    }
}

By way of explanation, the important events to handle are MapNotify and ClientMessage because there's two main things that have to be taken care of, the window has to have its hidden state removed on request (the xcb_delete_property call) and the parent window of the transient has to gain input focus (the xcb_set_input_focus call; note that the window that the transient is a transient for gains focus, not the transient itself) or Firefox will immediately hide the transient again.

It also seems to be important for the transients to be stacked above their parent so a WM should respect the ConfigureRequest events.

PS Even if this is the accepted answer, the code of it is for xcb, if you need the code for xlib check my answer below, with the code adapted for xlib, it does cover only the MapNotify event

Answer 2

Use xtruss — an easy-to-use X protocol tracing program

---

Overview

Any programmer accustomed to writing programs on Linux or System V-type Unixes will have encountered the program variously known as strace or truss, which monitors another program and produces a detailed log of every system call the program makes – in other words, all the program's interactions with the OS kernel. This is often an invaluable debugging tool, and almost as good an educational one.

When it's a GUI program (or rather, the GUI-related behaviour of a program) that you want to understand or debug, though, the level of interaction with the OS kernel is rarely the most useful one. More helpfully, one would like to log all the program's interactions with the X server in the same way.

Programs already exist that will do this. I'm aware of Xmon and Xtrace. But they tend to require a lot of effort to set up: you have to run the program to establish a listening server, then manually arrange for the target program to contact that instead of the real server – including some fiddly work with xauth. Ideally, you'd like tracing a program's X operations to be just as easy as tracing its kernel system calls: you'd like to type a command as simple as strace program-name arguments, and have everything automatically handled for you.

Also, the output of those programs is less easy to read than I'd have liked – by which I largely mean it's less like strace than I'd like it to be. strace has the nice property of putting each system call and its return value on the same line of output, so that you can see at a glance what each response was a response to. X protocol monitors, however, tend to follow the structure of the X protocol faithfully, meaning that each request and response is printed with a sequence number, and you have to match the two up by eye.

So this page presents xtruss, my own contribution to the field of X protocol loggers. It has a command-line syntax similar to strace – in its default mode, you just prefix "xtruss" to the same command line you would have run anyway – and its output format is also more like strace, putting requests and responses on the same line of output where reasonably possible.

strace also supports the feature of attaching to an already-running process and tracing it from the middle of its run – handy when something goes wrong with a long-running process that you didn't know in advance you were going to need to trace. xtruss supports this same feature, by means of the X RECORD extension (provided your X server supports it, which modern X.Org ones do); so in that mode, you can identify a window with the mouse (similarly to standard programs like xwininfo and xkill), and xtruss will attach to the X client program that owns the window you specified, and begin tracing it.

---

Description

xtruss is a utility which logs everything that passes between the X server and one or more X client programs. In this it is similar to xmon(1), but intended to combine xmon's basic functionality with an interface much more similar to strace(1).

Like xmon, xtruss in its default mode works by setting up a proxy X server, waiting for connections to that, and forwarding them on to the real X server. However, unlike xmon, you don't have to deal with any of that by hand: there's no need to start the trace utility in one terminal and manually attach processes to it from another, unless you really want to (in which case the -P option will do that). The principal mode of use is just to type xtruss followed by the command line of your X program; xtruss will automatically take care of adjusting the new program's environment to point at its proxy server, and (also unlike xmon) it will also take care of X authorisation automatically.

As an alternative mode of use, you can also attach xtruss to an already-running X application, if you didn't realise you were going to want to trace it until it had already been started. This mode requires cooperation from the X server – specifically, it can't work unless the server supports the RECORD protocol extension – but since modern X.Org servers do provide that, it's often useful.

Answer 3

Ok, i'm going to answer my own question after only 4.5 years and half.

I'm going to revise Mr Lightning Bolt answer, and adapt it for XLIB, keeping focused on what he said about the Transient window. The answer probably will not be complete, but at least with that code snippet, now i'm able to open firefox menus.

I will accept his question, since he proposed the correct solution.

As lightning bolt pointed the key is the MapNotify Event,so the window manager should accept that kind of events, and when it is generated it should:

1. grab any transient window with XGetTransientWindowForHint
2. if any transient window is found, we need then to set input focus to it using XSetInputFocus.

The complete code, in your MapNotifyHandler, should looks like:

Window trans = None;    
XGetTransientForHint(display, local_event.xmap.window, &trans); 
if(trans != None){
        XSetInputFocus(display, trans, RevertToParent, CurrentTime);
}