Editable Motion Path 
Edits the motion paths directly in the viewport. Select and move keyframe points with left mouse click and add or remove selection using shift. Change the colors for before a after the current frame separatly.
Colors
Change the colors of the motion path before and after the currnent frame.
Scale Keyframes Box
Scale the keyframes control box, this is influencing only its visualization.
Points
Hide and unhide the points.
Lines
Hide and unhide the lines.
Handles
Hide and unhide the bezier handles.
In Front
Always display the motion path in front, when this is unchecked, then the motion path will intersect with the objects in the scene.
Display Keyframe Numbers
Will show which frame is each keyframe. It will be visible only for the keyframes, but not all the frames.
Keyframe Distance Range
Control how sensitive is keyframe selection. when adding value to the distance, the keyframes will respond when the mouse is hovering further aways, and reducing the value will need to be closer to the keyframe point.
Frame range
Frame range of the motion path can use either scene frame range, all the keyframes, or a custom frame range. adjust manuel frame range with the Marker widgets. Around Frames will show only the frame before and after the current frame, depending on the before and after values.
Cyclic modifier
Editable motion path will also recalculate cyclic modifiers in realtime.
Hotkeys
Hotkeys that are currently available in 3d viewport are: In order to avoid colliding with Blender's viewport object interaction, Editable motion path Hotkeys are available only while hovering over keyframes
- Shift to add or remove from selection.
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Ctrl + Left Mouse Click - Add or remove keyframes. When a keyframe turns blue, it means it will be removed once the mouse is clicked.
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G or Left mouse click for grabbing and moving.
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R rotating the selection.
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S scaling the selected keyframes.
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XYZ are available for locking specific axis.
- Numpad . for zooming, available only while hovering on a selected keyframe.
- V - to change handle types to Free, Aligned, Vector or Automatic, similiar to graph editor / dopesheet hotkey.
- Ctrl + T - Change interpolation to Bezier, Linear or constant, similiar to hotkey T in the graph editor / dopesheet.
No keyframes handles are available
If handles are not available and you want to use them, then make sure interpolation is bezier, and they are turned on in the motion path display settings.
Edit rotation path
Motion path is influencing only location keyframes. However if you want to use it on the rotation curves, you can create a world space Temp Ctrl with a Track Target type
and edit the motion path of the track target.