Thunderbird

Add events to the calendar from VCS and ICS files

Save the files to disk.
Open Thunderbird and have the 'Today Pane' visible.
- Make sure the 'Events and Tasks' window is visible.
Navigate to the calendar event file(s) in a file explorer.
Drag and drop the files into the 'Today Pane'

Disable the titlebar

Select 'Edit' in the menubar (press Alt if it not visible).
Navigate to 'Settings.`
In the search bar, enter 'titlebar.' This will bring to view a section called 'Window Layout.'
Check 'Hide system window titlebar.'

Expand/collapse threads

The keyboard shortcuts to expand/collapse email threads are:

<left> expands current thread
<right> collapses current thread
* expands all threads
\ collapses all threads