Using
supports three different operation modes. First of all there is the construction mode used to set up points, lines, circles and the like. Then there is the drag mode which allows you to drag around constructed objects, showing the immediate effect of this movement. For example let's think of the circle of Thales. If you move the point opposed to the hypotenuse of the triangle along the circumference of the enclosing circle, you will see that the angle remains a constant 90 degrees. The third mode is the trace mode. You can mark points, so that they leave a trace when they move, they leave a trace where ever they moved over and you can see the way an object went. Next I'll describe each of those modes in a more detailed way.

The construction mode
On the left side of the main view (canvas) you find all the tools needed to draw geometrical objects. The first button, for example, shows a point and that is exactly what is drawn on the canvas if you select this tool by clicking on the button and then clicking somewhere on the main view.
All the tools are organized in groups to help you to find the tool you are looking for. If you choose the segment tool, for example, you can click on two different coordinates of the main view and a line segment will be drawn between those two points. If you choose the segment tool a second time, you can also click on existing points and thus construct segments between points you have created earlier.
If you are not sure what a tool is doing just move the mouse cursor over the button and wait for a second. The tool tip will tell you exactly what you can do with it.

The drag mode
The drag mode is very useful to demonstrate, how geometrical objects are related to each other. Right now only points can be dragged around. After every construction switches from construction mode back to the drag mode. Due to that you have to select a tool again to continue constructing some figure.

The trace mode
Points can have a trace mode which means they leave a trace over every place they move. You can apply the trace mode with the following tool . After that you can click on the point that should leave a trace. You can turn off the trace mode by applying the trace mode tool a second time.
This is an example of a point leaving a trace.
This is an example of a point leaving a trace.
This is an example of a point leaving a trace.

Tools to construct points
Construct a point.
Construct a point at (x;y).
Construct a point on a line or on a circle. This means that the point is attached to those objects.
Construct the point of concurrency of two lines, segments, rays and so on. Since you cannot drag around a point of concurrency, it is drawn as a little square.
Construct the bisection between two points.
Construct a mirror point. You can either mirror the point at another point or at a line. The first point you click on is the one that will be mirrored. Then you can click the line or the second point.
Rotate a point around another point. The angle will taken from a already constucted angle. The first point you click on is the one that will be rotated and and the second point is the center of the rotation.
Move a point. Click on a point that you want to move and then on a vector that defines the movement.

Tools to construct lines
Construct a segment between two points. The points do not need to exist, they will be constructed, as soon as you click on an empty spot.
Construct a segment. You also need to points for that.
Construct a triangle. You need three points for that.
Construct a vector. A vector is segment with a direction. You need a vector to move a point.
Construct a ray.
Constrcut a parallel line. You need to click on an existing line and then choose a point through which the parallel line should run.
Constrcut a perpendicular line. You need to click on an existing line and then choose a point through which the perpendicular line should run.

Tools to construct circles
Construct a circle. The first point is the center and the second point defines the diameter.
Construct a circle with a fixed diamter which will be entered through a dialog.
Construct an angle. You need three points for that where the second point is the center of that angle.

Tool to measure
Measure the distance beween two points.
Measure the area of a circle.
Measure the angle in degree.
Measure the slope of two points or a line.
Measure the circumference of a circle.

Other tools
This tool binds a point on circle or any kind of line.
This tool toggles the trace mode.
With this tool you can delete an object and all of its child objects.
With this tool, you can move the underlying grid.
Adding a text field to your construction.

Change the color and size
With these tools, you can change the color of an object.
With this tool, you can change the size of an object.