I am also confused about the role of filtering records via the context menu vs selecting records.
See the Filters topic. Try the examples in there. A filter restricts what a table window shows. If you have made a selection, for example, by ctrl-clicking a record or shift-clicking to select a swath of records, you can use the Filters command to tell the table to show only the selection, to show only those records not selected, or to show all records.
You can also apply filters based on logical criteria given the contents of a field. For convenience, those criteria are made available to you in a context menu where you can right click on a particular cell and the filter options are already loaded with the value of that cell. If you table with many cities all over the world and you only want those in Canada you can click on a Canada cell and choose Add Filter - Name = 'Canada' for instance.
Should the context menu be extended to provide the option to select records as well as filter then as transforms apply to selections not filtered datasets.
I don't think that would be a good idea, since a) context menus get confusing when they get too long, b) there are means now to make selections: learn to use the Select panel, as it is a very powerful tool (much more powerful than the select toolbar that was in 8) and it is always "on."
Maybe a better way could be within the View - Filter command, just below the list of active filters and above the Filter using Query option would be to add a Select using Filter command, which would replace the selection with what the filter is doing, that is (of course), a filter other than show/hide selection.
Should Ctrl-A select all records in a dataset or only those visible after a filter has been applied.
It should select all fetched records, not only those visible after a filter is applied. Think of it this way... should Ctrl-A select only those records a table window shows at the moment, ignoring those which are scrolled out of sight? Filters are a convenience for restricting what is displayed, not a selection methodology like queries or selections, where you can do Boolean operations on selection sets using the Select panel.
Directly connecting the user reference to the help menu would help.
It does. In the main menu choose Help - Documentation. With various windows open you can also press the F1 key to get a quick reference guide to shortcuts.
Could you also please fix the index on the help website.
? The illustration you attach indicates it is working. Click a letter to narrow it down to words starting with that letter, for example, S. Click a two letter combination to further narrow it down, for example, SO. Click on the numbers by each word to jump to pages that use that word.
Use Ctrl-F to Find within pages.
Edit: One more thing... one reason the documentation is online is so you can use your favorite search engine to search it. Google, for example, crawls the Manifold doc on a regular basis and they have extremely good search tools.
Use the site: command in the Google search bar. For example:
"orthographic projection" site: http://www.manifold.net/doc/mfd9
Finds desired pages instantly. Google and similar search engines also have the advantage of offering "did you mean..." alternatives when you misspell search terms, and even if you don't use site: it still is very good.