Hover over an Item 1: light blue x on left and right; pale blue arrows on each side.
Single click, whether over text or not: light blue x's disappear; medium blue circles appear outside of each side and corner. At this point any typing replaces all existing text.
Single click as above, followed by another single click: editing switches to the containing Class object.
Double click, whether over text or not: same as single click, but additionally existing text is highlighted. Again, any typing replaces all existing text.
Double click, followed by single click to the right of text: editing switches to the containing Class object.
Double click, followed by single click on text: cursor at single click point, and editing can proceed. The user can then hit the "End" key to move to the end. That achieves the desired insertion point, but only in three separate actions.
Specifically there doesn't seem to be a X coordinate you can click on that positions the cursor at the end of the visible text. At a certain X position of the mouse, the cursor is placed before the last character. Increase the X position by one, and it is interpreted as a single click to the right of text as above.
Triple click: interpreted as a double followed by a single.