The transparency element ensures making the program window transparent by drawing the screen contents in the portion below the window. The operation of taking the screen contents requires concealing the program window for a period of about 1 second (when the window is displayed). If the program window is not displayed in the 1:1 scale factor (i.e. if it is diminished or enlarged), then a screen portion will be taken corresponding to a window scaled 1:1 and having the same center as the program window has now.
Full Html Context Help of The Peter - Gemtree Software & Children Programming