Fixing borderless windows for KDE Plasma

[fire-eggs]

Borderless windows currently doesn't work on KDE plasma. The following chunks of code, pulled from feh is how it implements borderless windows, and it works on KDE.

typedef struct _mwmhints {
    unsigned long flags;
    unsigned long functions;
    unsigned long decorations;
    long input_mode;
    unsigned long status;
} MWMHints;

...
    memset(&mwmhints, 0, sizeof(mwmhints));
    if (opt.borderless || ret->full_screen) {
        prop = XInternAtom(disp, "_MOTIF_WM_HINTS", True);
        if (prop == None) {
            weprintf
                ("Window Manager does not support MWM hints. "
                 "To get a borderless window I have to bypass your wm.");
            attr.override_redirect = True;
            mwmhints.flags = 0;
        } else {
            mwmhints.flags = MWM_HINTS_DECORATIONS;
            mwmhints.decorations = 0;
        }
    }

...

    // ret->win is the result from XCreateWindow - a Window
    if (mwmhints.flags) {
        XChangeProperty(disp, ret->win, prop, prop, 32,
                PropModeReplace, (unsigned char *) &mwmhints, PROP_MWM_HINTS_ELEMENTS);
    }