Hi Roel,
Here's a neat trick I was recently able to add to the calendar.
I use my iPhone and iPad to create events, and realised I can make this process easier if I can get the "digits" keypad to pop when i select the start and end time boxes. As luck would have it the "decimal" keypad includes the digits AND a period, and the calendar code treats the period the same as a colon!
All I needed to do was edit /cal/pages/eventform1.php and add inputmode='decimal' into the span dTimeS and dTimeE elements.
Here's one in context:
<span id='dTimeS'{$hidden}><input inputmode='decimal' class='time' type='text' name='sti' id='sti' value='{$sti}'>
- Greig.