grid
figure
controls
x (horizontal grid)
y (vertical grid)
z (height of load)
angles
settings
auto correct extension
instruction

grid shows the XY position of the arm, and Z is the height.

on the grid, the red and green circle shows the minimum and maximum reach of the arm, given a certain height.

the figure shows the position of the arm, and the placement of the angles (red for arm A, green for arm B)

settings allow for the arm length to change. Arm A (red) has 2 parts, a1 is the one attached to the base. Arm B (green) has 3 parts, b1 is the one attached to the base.

auto correct extension will change the XY coords to the nearest position for which the arm can operate at that height