The editor's window shows all objects contained by the image being edited or root image. To change properties of this image (such as its name), use the "Edit/Image" option to display the “Image detail” dialog.
To reset the center point of the root image, first click on the “Select...” button in the properties dialog. Next, position the mouse in the canvas of the edit window over where you want the center point and click. The center can also be defined by editing the fields directly in the properties dialog.
The image detail dialog can be used to specify the size and angle of rotation of the image by editing the fields “Width”, “Height” and “Rotate by”.
Another way to resize the root image would be to use the "Edit/Select All" option to select all its shapes, then use "Layout/Group" to make a group. Dragging the square resize handles on the green selection box will resize this group. When the root image is appropriately sized, use "Layout/Ungroup" to eliminate the grouping.
See Also
Defining the center point of a shape
Using the Flip and Rotate tools