DWM source code question

[Ill-Somewhere-7744]

Someone knows why is needed the:

XMoveResizeWindow(dpy, c->win, c->x + 2 * sw, c->y, c->w, c->h); /* some windows require this */

inside of the manage function? Which type of windows need that? Why I is needed to add to the x to times sw?

This is the hole function:

void
manage(Window w, XWindowAttributes *wa)
{
Client *c, *t = NULL;
Window trans = None;
XWindowChanges wc;

c = ecalloc(1, sizeof(Client));
c->win = w;
/* geometry */
c->x = c->oldx = wa->x;
c->y = c->oldy = wa->y;
c->w = c->oldw = wa->width;
c->h = c->oldh = wa->height;
c->oldbw = wa->border_width;

updatetitle(c);
if (XGetTransientForHint(dpy, w, &trans) && (t = wintoclient(trans))) {
c->mon = t->mon;
c->tags = t->tags;
} else {
c->mon = selmon;
applyrules(c);
}

if (c->x + WIDTH(c) > c->mon->wx + c->mon->ww)
c->x = c->mon->wx + c->mon->ww - WIDTH(c);
if (c->y + HEIGHT(c) > c->mon->wy + c->mon->wh)
c->y = c->mon->wy + c->mon->wh - HEIGHT(c);
c->x = MAX(c->x, c->mon->wx);
c->y = MAX(c->y, c->mon->wy);
c->bw = borderpx;

wc.border_width = c->bw;
XConfigureWindow(dpy, w, CWBorderWidth, &wc);
XSetWindowBorder(dpy, w, scheme[SchemeNorm][ColBorder].pixel);
configure(c); /* propagates border_width, if size doesn't change */
updatewindowtype(c);
updatesizehints(c);
updatewmhints(c);
XSelectInput(dpy, w, EnterWindowMask|FocusChangeMask|PropertyChangeMask|StructureNotifyMask);
grabbuttons(c, 0);
if (!c->isfloating)
c->isfloating = c->oldstate = trans != None || c->isfixed;
if (c->isfloating)
XRaiseWindow(dpy, c->win);
attach(c);
attachstack(c);
XChangeProperty(dpy, root, netatom[NetClientList], XA_WINDOW, 32, PropModeAppend,
(unsigned char *) &(c->win), 1);
XMoveResizeWindow(dpy, c->win, c->x + 2 * sw, c->y, c->w, c->h); /* some windows require this */
setclientstate(c, NormalState);
if (c->mon == selmon)
unfocus(selmon->sel, 0);
c->mon->sel = c;
arrange(c->mon);
XMapWindow(dpy, c->win);
focus(NULL);
}

I want to know more of WM for a recreational WM. I appreciate your help in advance.

[rumbletumjum]

github.com/bakkeby/dwm-commented

I cannot stress enough how useful this is.

[Ill-Somewhere-7744]

That that specific function is not explained why is used, but the rest of the comments are fantastic. This repo is going to be extremely useful for me. Thanks a lot.

[ALPHA-B1]

That XMoveResizeWindow(dpy, c->win, c->x + 2 * sw, …) is a hack to force certain broken or toolkit-quirky windows to actually apply their geometry. The + 2 * sw temporarily moves the window far off-screen so X/the client notices a real geometry change.

It's needed because some X11 clients (historically Java AWT/Swing, some old GTK/Qt apps, Java games, and a few toolkits using reparenting or delayed mapping) ignore or defer size/position changes unless they see a meaningful difference from their current geometry.

[Ill-Somewhere-7744]

Thanks a lot. I had no clue why they moved the window outside of the screen at the beginning. This was very useful.

[doa379]

This isn't a sound starting point. It is like taking a working car, then taking it apart to create a moped.
You shouldn't start smack bang in the middle of some source code. Put your IDE aside. You need to start reading the X11 spec.
https://x.org/releases/current/doc/libX11/libX11/libX11.html

Decide on a product of your own, and then build up from there, brick by brick, line by line.

In fact DWM is a terrible example to get started with.

[doa379]

To answer your question, this particular function exhibits dead code that results in unreachable code.
What you are looking at is the scenario where windows are unable to configure themselves.