fix #7654 - in a large sage worksheet "every few seconds the part of …

…the file visible on-screen scrolls or jumps further down to a part that I'm not currently working on."

src/packages/frontend/editor.coffee

@@ -499,9 +499,12 @@ class CodeMirrorEditor extends FileEditor
                 showCursorWhenSelecting : true
                 extraKeys               : extraKeys
                 cursorScrollMargin      : 6
-                viewportMargin          : 300 # larger than the default of 10 specifically so *sage worksheets* (which are the only thing that uses this)
+                viewportMargin          : Infinity  # larger than the default of 10 specifically so *sage worksheets* (which are the only thing that uses this)
                                               # don't feel jumpy when re-rendering output.
                                               # NOTE that in cocalc right now, no remaining non-sagews editors use this code.
+                                              # with images, even using a viewport of 300 causes major jumpiness problems with images.
+                                              # See https://github.com/sagemathinc/cocalc/issues/7654
+                                              # Browser caching may have changed in newer browsers as well making 300 feel jumpy in "modern times".
 
             if opts.match_xml_tags
                 options.matchTags = {bothTags: true}

src/packages/frontend/package.json

@@ -198,6 +198,7 @@
   "scripts": {
     "preinstall": "npx only-allow pnpm",
     "build": "rm -rf dist && NODE_OPTIONS=--max-old-space-size=8192 tsc  --build && coffee  -m -c -o dist/ .",
+    "build-coffee": "pnpm exec coffee -m -c -o dist/ .",
     "tsc": "NODE_OPTIONS=--max-old-space-size=8192 ../node_modules/.bin/tsc  --watch  --pretty --preserveWatchOutput ",
     "test": "npx jest dist/",
     "prepublishOnly": "pnpm test",