Rainlendar is a customizable calendar application which stays out of your way but keeps all your important events and tasks always visible on your desktop
Display problem in Debian Linux
To fix the problem:
Options
→ Advanced
→ Windows
Transparency type
= Native
[Rainlendar Forum]
Options
→ Skins
→ Select any item in "Active skins" → Settings
→ Global variables
(Skin name)::Large
= ON
Options
→ Skins
→ Active skins → (Skin name) - Day/Week View
→ Settings
→ Window variables
Time item height
= 60
(30
is default)