an open source PCB editor for Microsoft Windows, released under the GNU General Public License.

How to work with selection mask?

Items in the layout are selected for editing by clicking on them or drawing a rectangle around them with the mouse. Since items may overlap one another, sometimes it may be difficult to select exactly the item(s) that you want. In this case, the selection mask can be used to enable or disable the selection of different item types. It consists of a list of these types, with a colored box next to each one. A green box means that the item type can be selected, while a red box means that it can’t. You can toggle the state of each box by clicking on it. You can invert the mask by clicking on it with the control button held down.

Freepcb selection mask

Selection objects.

You can select several objects by clicking on them in turn with the CONTROL key held down. With the selection frame can also be select objects. Move the mouse from the top left edge of the screen to the bottom right edge. If you want to deselect several objects, drag mouse on them in the opposite direction.

If you already have more than one object selected, you can add new selected objects to the existing objects with the selection frame without pressing the CONTROL button.