Pencil is built for the purpose of providing a free and open-source GUI prototyping tool that people can easily install and use to create mockups in popular desktop platforms. This version can be installed along with 2.0.x version without any problem. Optional features ELECTRON (default=no): This requires electron, available in SBo. Use pencil3 with some version of electron previously installed in the system. Otherwise the SlackBuild uses and downloads electron required for pencil3. BINARY (default=no): Use it to create a binary package. This option requires downloading electron for the architecture of your system, close to 40MiB. You can install the electron package from SBo with the INSTALL_ZIP=yes option, to avoid the download. If you need to use any option do something like: ELECTRON=yes ./pencil3.SlackBuild