clear (\033[m) is put after each call to tb_change_cell

[robem]

try the following code snippet in normal color mode:

for (color = 1; color < 8; color++) {
    tb_change_cell(color, 2, 'X', 2, color);
}
tb_present();

The forground color changes after the first tb_change_cell() to white.

Only the bg (color) parameter changes that's why the code calls write_sgr_bg() but somehow a clear was introduced earlier so that the foreground value is negated/overwritten by the default one.

I tested it against e742ddb5908dff205dde338b50f3a92ec2e844e1 and it worked.
So my commits introduced a bug.
I will look into it tomorrow evening.