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
The 16 first entries in the 256-color array are the regular and bright
colors. However, since they can be changed (eventually) at runtime, we
can't statically initialize the 256-color array.
Instead, pick the regular+bright colors directly from the terminal
struct. I.e. the first 16 entries of the 256-color array are now
unused.
The grid is now represented with an array of row *pointers*. Each row
contains an array of cells (the row's columns).
The main point of having row pointers is we can now move rows around
almost for free.
This is useful when scrolling with scroll margins for example, where
we previously had to copy the lines in the margins. Now it's just a
matter of swapping two pointers.
* action() returns void - this gets rid of checks in vt_from_slave()
* split up ACTION_PRINT into ACTION_PRINT (ASCII) and ACTION_UTF8_PRINT
ACTION_PRINT is on the hot path, and we want it streamlined.
* Remove run-time checkout for unimplemented state transitions, as we
shouldn't have any of those left.
* Don't re-load current VT state on each iteration in vt_from_slave()
