Broken: all versions up to current trunk
Short description of error
Hsv color adjust curve widget (in "hue correct" node and the corresponding VSE strip modifier) has a hue color gradient background. When using the zoom buttons on the widget, the background gradient does not scale according to the zoom, rather it stays at fixed size, and fills the whole widged area only if it is viewed at lower left corner, otherwise the ending point of the gradient is visible and the gradient doesn't match the curve points.
Exact steps for others to reproduce the error
Open blender, switch to compositor and enable nodes. Add a hue correct node, zoom in and move the curve widged navigation around. Notice obvious mismatch between the gradient's location and zoom level, and that of the curve points, and how they don't match.
Apply attached patch and test again to see the problem fixed.