Author: Jonas Bilinkevicius

Ok, I have a Memo with a bunch of lines, but how do I know the first visible line 
of it? 

Answer:

this is very simple 
1   
2   FirstLine := Memo1.Perform(EM_GETFIRSTVISIBLELINE, 0, 0);


The return value is the zero-based index of the uppermost visible line in a multiline edit control. For single-line edit controls, the return value is the zero-based index of the first visible character.