Panning:

Press middle mouse button (wheel)
or
press Alt + left mouse button

Scaling:

Date timeline – scrolling mouse wheel.
By vertical timeline – press Ctrl(Command on MacOs) + mouse wheel scrolling.

Editing:

To go to editing mode please press the «Editable» button on the panel menu.

The start and end of the task bar can have two different forms:

rectangular shaped – which means that the task start or end time has a meaning that was set manually;
round shaped – the task start or end time was not set by the user and is calculated automatically.

You can set or change the start time or duration of a task by drag-and-dropping or stretching the corresponding task bar into the diagram.
You can set/reset fixed task values using context menu.

Linking:

You can link task only in editing mode.

To link two tasks you have to capture the circle at the end of the task bar or stretch the line from any point of the task bar holding Ctrl. After the link is set you will see a colored pointer, if necessary time expenditure characteristics of task will be recalculated.
To reset links press Drop link(s) in the context menu.

Undo - Ctrl + Z
Redo - Ctrl + Y