4  *

     5  * dynamic window manager is designed like any other X client as well. It is

     6  * driven through handling X events. In contrast to other X clients, a window

     7  * manager like dwm selects for SubstructureRedirectMask on the root window, to

     8  * receive events about child window appearance and disappearance.  Only one X

     9  * connection at a time is allowed to select for this event mask by any X

    10  * server, thus only one window manager instance can be executed at a time.

    11  * Any attempt to select for SubstructureRedirectMask by any connection after

    12  * another connection already selected for those events, will result in an

    13  * error generated by the server. Such errors are reported through calling the

    14  * current X error handler.

    15  *

    16  * Calls to pop an X event from the event queue of the X connection are

    17  * blocking.  Due the fact, that dwm reads status text from standard input, a

    18  * select-driven main loop has been implemented which selects for reads on the

    19  * X connection and STDIN_FILENO to handle all data smoothly and without

    20  * busy-loop quirks..  The event handlers of dwm are organized in an array

    21  * which is accessed whenever a new event has been popped. This allows event

    22  * dispatching in O(1) time.

    23  *

    24  * Each child window of the root window is called a client in window manager

    25  * terminology, except windows which have set the override_redirect flag.

    26  * Clients are organized in a global doubly-linked client list, the focus

    27  * history is remembered through a global stack list. Each client contains an

    28  * array of Bools of the same size as the global tags array to indicate the

    29  * tags of a client. There are no other data structures to organize the clients

    30  * in tag lists, because a single global list is most simple. All clients which

    31  * have at least one tag enabled of the current tags viewed, will be visible on

    32  * the screen, all other clients are banned to the x-location 2 * screen width.

    33  * This avoids having additional layers of workspace handling.

    34  *

    35  * For each client dwm creates a small title window which is resized whenever

    36  * the WM_NAME or _NET_WM_NAME properties are updated.

    37  *

    38  * Keys and tagging rules are organized as arrays as well and defined in the

    39  * config.h file. These arrays are kept static in event.o and tag.o

    40  * respectively, because no other part of dwm needs access to them.

    41  *

    42  * The current mode is represented by the arrange function pointer which wether

    43  * points to dofloat or dotile.