The command-double-click and option-double-click and contextual menu behavior depends on the a Finder Preference settings.
When "Open folders in tabs instead of new windows" is checked:
- command-double-click opens the folder in a new tab in the same window
- option-double-click opens the folder in a new window and closes the previous window
- contextual menu has "Open In New Tab" as first item
- contextual menu with option key held down has "Open In New Window" as first item
When "Open folders in tabs instead of new windows" is un-checked:
- command-double-click opens the folder in a new window but does not close the previous window
- option-double-click opens the folder in a new window and closes the previous window
- contextual menu has "Open In New Window" as first item
- contextual menu with option key held down has "Open In New Tab" as first item
If you ever forget to use any of the options above and accidentally open a folder with a simple double-click your window position and size will be change. You will have to move it back and resize it back the way it was. Argh!!!
The real problem with this is that it is destructive - you can't undo the changes to the window.
I really miss the original Finder behavior which was:
- double-click opens folder in a new window
- option-double-click opens folder in a new window and closes previous window
And, the window position, size, and view was never changed.