Windows 10 and FormClose lazarus / 34-Windows ---------------------------------------------------------------------- rick2691 ยท 2019-07-04 15:23 @metis HeapTrc-Unit (-gh Switch): memory blocks allocated and freed equal each other unfreed memory blocks equal zero true heap = 229376 true free heap = 229248 true free heap should = 229376 ==== SetExceptionMask: I did not put it at the start. I put it at the start of FormCreate. Calculator.7z: He uses a different approach but it looks essentially the same by my review. ================= attached: Laz-CmdRPN - Copy.zip This is the entire project. It is 32bit. It is a scientific RPN (reverse-polish-notation) calculator. Entry example: 32 enter 20 plus ... the result is 52.