Concatenate Images _ JAVA - open to bidding

Hi guys, 0 - Introduction: Sorry about the grammar. I am not a native english speaker ( i'm brazillian ) I made a program that print the screen, open it in a frame and allows me to select an area of the image. I added a (Save) button that when it is pressed the program write the selected area of image in a new file and save it. [code] [/code] 1 - What i want it to do: I want to use a list of rectangles to store all the selected images and when i pressed the (OK) button the program will concatenate it all in an single horizontal line (at the same file). But i want more than this: i want to: Create a new button that when it is pressed it starts to save the nexts rectangles (images) in another list and when i pressed [ (OK) button or this button again ] the program will concatenate this file under the first horizontal line (all at the same file).