Until now, hidden columns were displayed as visible in the context menu.
An easy way to reproduce this is:
- Open the TextEditor
- Ctrl-O to open the file selector
- Switch to table view
- Right-click the header
Expected behavior:
Hidden columns like 'Owner' and 'Group' should not have a checkmark,
because they are hidden.
Actual behavior: They did have a checkmark. Clicking on it to 'hide'
the already hidden column removed the checkmark, but was a no-op to the
table view.
This commit fixes this behavior, by correctly initializing the context menu,
and properly updating the context menu if external code calls
'set_column_hidden' later.