In Trident latest release on Codeplex we don’t have any free canvas where we can drag activities.
Regarding your query - <<if we are building a big workflow, it is not very convienent, we have to scroll right and left to connect the different actvities.>>
You can use the subsection feature of trident that is designed to group activities as one entity. You can collapse/expand a sub section.
When you collapse a subsection it will hide all activities inside the subsection and shows a place holder.
To create a sub section of group of activities you need to select the activities which have to be grouped. Then right click on selected activities and then click “create sub section” menu.
Hope this answers your question.
Trident Support Team