Similar to Shrink / Extend Line, trims or lengthens a group of line so that they meets another object. Double lines and multi lines can also be used.

Select two points to draw a temporary "fence" that passes over all of the lines you want to shrink or extend. Be sure the fence intersects each line closest to the endpoints you want to move.
The endpoints that will move are indicated by small squares. Select the object that the lines are to meet.
The endpoints of the lines meet the selected object.

Note: You can use Multi Shrink / Extend Line on splines and Beziers, however the extension will be straight element of the curve, not curved continuations as they are with arcs.

Note: Most standard Modify tools, such as Trim, Split, and Meet 2 Lines, will work with walls.