Thank you George.
Yes, I messed that up. I meant ICS, of course, a database where all items are stored.
1. Thank you for uploading an addon, but I need to downgrade Rainlendar first, I have got an "This skin addon is for version 1.3. of the skin. The installed version is 1.9." error.
2. Without ICS - just meant uploading rainlendar files with clear ICS or just without it. Doesn't really matter

The second problem is all about a useless step - to choose a correct ics file to save the item - when clicking to specific to-do list that should already be connected with correct ics file. Have I expressed the problem correctly, this time? May be your addond solves the problem, I don't know yet.
Thank you for helping me.
Sebastian