Hi Laurent, Thanks for the detailed explanation. I quickly checked on the older Windows system and the Java 11 window was the same size as the Java 8 one, implying no scaling was going on (I guess just because it has a lower resolution monitor) - so that confirms your hypothesis.
If I use -Dsun.java2d.uiScale=1.0 that's OK for my laptop, it doesn't matter if the window is a bit small. However I believe some higher end systems have much higher scaling factors (2x, 3x?). Is there a general way to specify a 1px line regardless of scaling, because in my case I don't mind too much if it's a 'hair-line'? By the way, my actual application doesn't have 65000 lines but it draws 3 graphs with about 3000 points, which makes it noticeably slow when resizing the Window. I suppose I should look into cutting down the number of points somehow... Pete
