Well this is embarrassing; the sub-parameter versions of the 38/48 SGR
escapes all required an extra ‘:2’ that wasn’t supposed to be there,
causing all the other sub-parameters to be shifted one step to the
right.
That is, foot expected e.g. 38:2:2:r:g:b, or 38:2:5:idx when the
correct sequences are 38:2:cs:r:g:b and 38:5:idx.
I.e. I mixed up the color-space ID (cs) of 38:2 with *type* of color:
RGB or indexed.
In addition to fixing this, this patch also adds support for a
“bastard” version of the sub-parameter based RGB escapes, where the
color-space identifier has been left out: e.g. 38:2:r:g:b. This
sequence is invalid, but applications tend to “forget” the color-space
ID...
This implements OSC 4, 10, 11 - change <color>/foreground/background,
and their corresponding 'query' variant (which was already implemented
for OSC 10/11).
It also implements OSC 104, 110, 111 - reset
<color>/foreground/background.
Set corresponding terminfo entries to signal this support to clients.
I.e. it issues a \E[2 q regardless of what we've configured the
terminfo Se entry to.
So, make \E[2 q mean "the user configured cursor style" (which
defaults to 'block').
According to the specs, \E[0 q means a blinking block cursor. However,
since it also states that \E[1 q *also* is a blinking block cursor,
and that it is the default, *and* given that fact that parameter-less
CSIs typically means "reset", let's make it mean "reset to the user
configured cursor style".
Use our own escape sequence for the 'flash' terminfo entry.
Implemented by arming a timer FD and setting a boolean that indicates
we're currently "flashing".
The renderer draws a semi-transparent yellowish layer over the entire
window when "flashing" is active.
22;0|1|2t pushes the current window title/icon to the stack, while 23
pops it.
The second parameter, 0|1|2 has the following meaning:
0 - push/pop icon+title
1 - push/pop icon
2 - push/pop title
