scenario: position a tall node with its top within the viewport, and extending past bottom of viewport press page-down
Before this commit we were seeing strange patches of empty space above the old top.
7JZFRO5FU57TYQOBZXVLISILKAYDQYTTGZXCPGOZNW3GAU7INQBQC EXZESF4IFJIIMKDIWKXZ3FQM5GYCIGQJEFDENCLCO5FHE5ZPABNQC 2N4JZKVTSJJJIXM2VVCU5INC4IGY7J6FF4JD3TAFK5THD2QWSQPQC 54Y4QQG3ETC4YMUDDJBQO4SLFMX3NOLI5PRGVHUY2DVGZAUJBZVAC QJAYOFWY7V4BWVLJMEDCCBC2HX4BDAZI6PQVLWCLYRHWGMOBFTVAC TBB7GHINPHDTKI3B6U3M2OF7UGQ5V5DUHODB7UNKNZMBA4NWKUFAC BF7TW3EKRIDYC6J2Q2J4YOBAVQF55Y3H6KGZIHNXMH4N72MR6GXQC O6D22PJBXFE5XGW27UD7NDIMQYL4NXH4C4T2E73F2NXUSEB4W7QQC print('modified screen_top to', node.editor.screen_top1.line, 'at', node.editor.top, 'vpx')else-- adjust editor to start rendering near top of viewport--? print(Viewport.y)node.editor.top = Viewport.y%node.editor.line_heightif node.editor.top > 0 then node.editor.top = node.editor.top - node.editor.line_height end--? print('top', node.editor.top)