This adds Python 3.9 and 3.10 typing syntax to files that import
attributions from __future___. Python 3.9 should be able to cope with
the 3.10 syntax, but Python 3.8 will no longer work.
On Windows/Mac, install the latest Python 3.9 version from python.org.
There are currently no orjson wheels for Python 3.10 on Windows/Mac,
which will break the build unless you have Rust installed separately.
On Linux, modern distros should have Python 3.9 available already. If
you're on an older distro, you'll need to build Python from source first.
Decouples changes of the current element and changes of the selection.
Introduces `browser.current_card` which has previously been amalgamated
with the previewer card `browser.card`.
The latter triggers `selectionChanged()` unreliably, probably due to the
aggregation of chronologically close events, causing problems in
tracking `_len_selection`. `reset()` never emits signals.
`len(self._view.selectionModel().selectedRows())` is slow for large
selections, because Qt queries flags() for every selected cell, so we
calculate the number of selected rows ourselves.
- Cache the result of 'table.len_selection()'
- Update this cache manually when a row was deleted or restored
- Emit 'dataChanged()' after such a change to fix flags not updating
correctly to the shortcut in 'model.flags()'
- Remove/retsore focus if the current element was deleted/restored
The previous behaviour when a non-sortable column was clicked was to
trigger the sorting routine, which was usually a no-op, but would
reorder rows if the configured sort column was hidden.
