Quote:

- Colour support (Foreground & Background, remember that you can only change the colour of 8 characters at once, so if you have four 16x16 tiles to colorize you can only put two different colors, as a 16x16 tile requires four characters to be displayed so 4 * 4 = 16 ---> 16 / 8 = 2 Colors).

What do you mean?
Why in scr1 you cannot edit 4 tiles each with its foreground and its background? this leads to 8 colors.
What about scr2 support?
Why not having a small preview screen where one can place the tiles in different combinations
and have a glance on how they look like together ?
What about the possibility to edit a complete tile set?

To change foreground and background colours on the character table you have to write

VPOKE BASE(6) + X, < New colour >

where X is a number between 0 and 31

when X = 0, you can set the foreground and background color of the characters starting from CHR$(0) TO CHR$(7)
when X = 1, you can set the foreground and bacground color of the characters starting from CHR$(8) TO CHR(15)
and so on, with X=2 -> CHR$(16) TO CHR$(23), X=3 -> CHR$(24) TO CHR$(31), ...

Displaying one 16x16 tile requires to redefine 4 characters; so in a group of 8 characters you can have up to two 16x16 tiles (or four 8x16 / 16x8 tiles, or eight 8x8 tiles)

But you colud try to compose 16x16 tiles using 4 chars from any of the 32 groups.
Moreover you could design chars that can be composed in many ways....

Scr1 is very poor, but allowing only one color for 4 tiles constrains the design more
than the HW itself permits.

I'll go for a SC2 editor with an option to save as SC1 - that'll provide the best functionality.

Ok, I'll add SCREEN 2 support ASAP. I've just to understand how to write MSX code to handle multicolor gfx properly