In-game go to Settings > Visual Settings > UI Visibility > Off
- Download and install GeDoSaTo programm
- Go to Whitelist and copy Trine1_32bit || Trine 1 Enchanted Edition
- Paste it to the User Whitelist
- Go to Edit Keybindings in GeDoSaTo and unquote the toggleHUD bind. For example, toggleHUD VK_DIVIDE.
- Activate the programm
- In-game, press Divide (/) to toggle HUD on/off