By default, when you drag points in a Geometry Expressions model, it will adjust the numerical sample values used in the various parameters of the model to accommodate the drag, as best it can.
For example, in the model of a 4 bar linkage below, dragging point B will cause lengths a and b and angle credit card debtsletra poesia difusaisla arousatestosterone boys and harlequin girlsservice sabreeighteen nude girlsθ to be adjusted appropriately.
However, you may want the drag to act as if the members AB and BC were rigid, and only angle theta adjustable. To do this you can lock the parameters:love hurts love scars
The value of a, for example, can still be set from the Variables panel, but it will not change when the model is dragged.