What do you think about adding a "Find/Search" function to the built-in viewer? I find myself opening up text files for quick viewing using F3, but there is no way to search within the file.
Thank you for your feature request. It has been forwarded to our software developers and we will consider extending standard features of built-in viewer application.
Same behaviour here about panels size. It's 25/75 after start. Version Version 1.0 (1344) - Commander One PRO.
We assume that you are using the very first version of Commander One, or the edition from App Store, under Mac OS El Capitan. That is why you are experiencing those problems.
If you use version from our web-site, navigate to Commander One main menu --> Check for Updates... and make sure that you are using the latest version. Then, go to Preferences --> Advanced tab, and enable all options, under "Save on quit" list.
In case if you are running App Store edition of Commander One, the only thing we can suggest is waiting till the upgrade with El Capitan compatibility is released.
I've been testing your application and there are some options that I would like to add:
- To decompress a file using another compressor (keka) or to open with ... (application list)
- To decompress files they can be left in the background to perform other tasks
- To have an option to check compressed files
~ I would like to inform you that "Open with" option has been added to Commander One since the latest upgrade of the edition from our web-site.
~ In order to decompress files in the background, open archive in Commander One with double-click, to view its content. Then, drag a file out of the archive or use Copy (F5 def.) option, and queue the copying with F2 key. Here you may find more information about queuing:
http://wiki.eltima.com/user-guides/commander/queue.html~ We are sorry for possible misudnerstnading, but you can check the compressed files withot a problem. Just open the archive in Commander One to see its content, then choose a file and hit View button (F3 def.), and the file will be decompressed and opened in viewer.
My 2 cents on missing features:
- Keyboard shortcuts currently only cover a subset: e.g. going up a folder is customizable but entering a folder is not (e.g. I prefer navigation with left/right arrow keys)
- Quick Filter is my most important productivity feature: instead of only typing some letters of the start of a filename, with Quick Filter you can customize whether it's possible to type letters e.g. from the middle of a filename (useful if many files in a folder have the same prefix like com.apple.). Quick Filter typically also allows to really narrow the file list to the currently matching characters typed.
...
Besides that I +1 the other replies here like customizable editor, sync dirs, compare by content 
Thank you for your requests, they have been forwarded to our developers along with the others.