Qubes OS version
R4.0

Affected component(s) or functionality
qubes-desktop-linux-i3 version 1000:4.16-9.fc25.

Brief summary
It seems the default_border setting and the border command are ignored.

How Reproducible
Every time

To Reproduce
Steps to reproduce the behavior:

1. Add the following lines to ~/.config/i3/config in dom0:

   default_border pixel 10
   for_window [ class="Firefox" ] border pixel 30
   

2. Open a terminal
3. Open a Firefox window

Expected behavior
The terminal window should have a border size of 10 pixels.

The Firefox window should have a border size of 30 pixels.

Actual behavior
Border size is unaffected in both cases.

Additional context
I think this is caused by the following line in the Qubes patch for i3:
https://github.com/QubesOS/qubes-desktop-linux-i3/blob/93b8b1ba9d41f56c85bea4752a7270fe1468fb36/0001-Show-qubes-domain-in-configurable-colored-borders.patch#L180

Following the Git blame, it seems that this was first introduced when bumping the upstream version to 4.16. Comparing it with the patch for version 4.15 and using the then-upstream repo as reference, it looks like the previous behavior was to only override the width when the upstream one set it to a constant value, and using the user-supplied value in all other cases. The bump to 4.16 changed this to be overridden in all instances, presumably by mistake.

In order to follow a similar behavior as in previous versions, the patch should instead produce code akin to:

static int border_width_from_style(border_style_t border_style, long border_width, Con *con) {
    if (border_style != BS_NONE && border_width >= 0) {
        return logical_px(border_width);
    }

    const bool is_floating = con_inside_floating(con) != NULL;
    /* Load the configured defaults. */
    if (is_floating && border_style == config.default_floating_border) {
        return config.default_floating_border_width;
    } else if (!is_floating && border_style == config.default_border) {
        return config.default_border_width;
    } else {
        /* border_style is BS_NONE or the default styles are not applicable  */
        return 3;
    }
 }

(NOTE: The above code has not been tested.)

Solutions you've tried
I configured both with really exaggerated border sizes (as above) to make sure I definitely would notice if it worked.

I have confirmed that the Firefox window is matched correctly by modifying other settings on it with for_window, it's just the border command that is broken.

I have successfully used these settings in i3 on non-Qubes machines previously.

Relevant documentation you've consulted
https://i3wm.org/docs/userguide.html#_default_border_style_for_new_windows
https://i3wm.org/docs/userguide.html#_changing_border_style
https://i3wm.org/docs/userguide.html#for_window

Related, non-duplicate issues
None