lukemorte
...ok I realized I can find that tool in Shortcuts manager as Edit Current Operation but now I have another problem and it seems like a bug: This tool is triggered by key Enter as default and it works perfectly. When I change this shortcut for example to Space or key D or X it sometimes works but most of the time it's not triggered by pressing that key. So for example if I continuously press two keys 'S' and 'Enter' it's switching between Select tool end Edit current tool (the handles). But if I assigned to Edit current tool key 'D' for example and now I try switching between Selection tool and Edit current tool, it works only once and only sometimes and then nothing. I have no idea what's wrong with this tool / shortcut assignment. Is there something wrong am I doing ? Thank you 
Maybe you have to change 'Accept' to the same key, or hit whatever key is assigned to 'Accept' to complete the selection?
Edit after further investigation:
Edit Current Operation doesn't have a key assigned to it by default, so I don't think the 'Enter' key is actually activating that operation. The show handle action is probably hardcoded to the 'Enter' key.