I use the latest version of your scheduler. In am located in the Netherlands, GMT +01:00 (Central Europe)
When you have set: scheduler.config.start_on_monday = false;
And you are in the week the daylight saving time starts (march 30 2014).
Than resizing activities has a gap of 1 hour.
Also creating new activities on days after Sunday goes strange. When you drag your mouse downwards the activity starts drawing 1 hour to late.
Hope you can fix this?