ok, i think i had to explain the methodology a bit more, as it is not completely clear.

Step 1

now we need to store and recall the color of any character on the screen, therefore we have to add another dimension to the staticChars matrix to store it's color.
for memory optimizations we won't store the color itself in that matrix but only a reference to it being {null: not specified, 0: dayColor, 1: dateColor, 2: messageColor, 3: clockColor}
for performance measures and to skip usage of a switch case in calculateColor() function, we have to add another array called colorPallet that holds all 4 static colors in the previously given index(0:day, 1:date, 2:message, 3:clock)
in the calculateColor() function, you should have a look up into the newly structured staticChars matrix and if the value corresponding the character color was not null, look up the color from colorPallet array and return it.

Step 2

we need to input the colors properly and store theme inside the colorPallet, for that, for onChange of ui_..._higlight and ui_..._textColor you need to call 2 functions in this order
1. another new function called fillColorPallet() this function will fill the array of colorPallet from options object.
2. updateMask()

now we need to fill the staticChars matrix. there are two scenarios