You can customise the Menu Map system to create clickable areas and the clickable areas can launch external applications. Inside the help file, search for topics beginning with "Menu Map..."
You can also add a user menu to the front menu or to most of the sections of the software, using scripting. The topic to read would be "Run Task Menu Script".
The script functions that can be used to launch an external application include RunApplication() and/or Shell()
These functions are documented in the Visual Builder help file.