How to collapse all trees in htop?

Possible as of 3.1.0 (not yet in all distributions)

As of htop --version 3.1.0, you can in fact toggle-collapse all branches of the tree view (F5) using hotkey * (asterisk). The release happened only on 2021-09-21, so most 2022 linux distributions (except those with rolling releases) are about to receive the updated version with their next release.

For example, the Ubuntu package overview for htop shows that

• ❌ Ubuntu 21.10 (impish) and 22.04 LTS (jammy) both stick to version 3.0.5 and only
• ✅ Ubuntu 22.10 (kinetic) ships with 3.2.1.

And just for completeness sake:

• Collapsing and expanding invidivual tree nodes was/remains possible using - and +
• To review all key bindings in your version of htop, simply enter the help screen (? or h or F1)

AFAIK "t" is the hotkey for expansion and collapsing tree view in htop.

You can use the * key

This was implemented in version 3.0.5 (2021-01-12)

• https://github.com/htop-dev/htop/issues/68
• https://github.com/htop-dev/htop/pull/525

It is still not implented. Moreover, F5/F6 were "killed".

Besides, +/- do not work from keypad. As a result, the whole idea of tree-view became useless (as for me it is the only possible way to represent a lot of processes)