I write several pieces of text. Sometimes when a rectangular region of one piece of text overlaps another text, the color of the other texr changes. It doesn't happen always, only sometimes. Can anybody explain to me what it depends on?
Thanks in advance

The only thing that occurs to me is that one or both blocks of text must contain some transparency. Or possibly the layer has a Blended Mode besides "normal".

Does this happen as you type? Or is it just after you finished typing and move the blocks of text around? Are you using Layers?