Tips for MacBooks and other HiDPI displays

Using the middle mouse button with a trackpad
The QT GUI instrumentation has a menu that can only be accessed with the middle mouse button. A MacBook with a trackpad can't trigger this menu without the use of a third-party tool. One such tool is MiddleClick, which lets you trigger a middle click with a three-finger tap on the trackpad.

Increasing the font size
The text of the GRC canvas can be changed by editing your  file. Find the  section and add a   setting:

[grc] canvas_font_size = 14

GNU Radio 3.7
GRC in GNU Radio 3.7 uses GTK 2.0. The UI font size (all the text that's not part of the canvas) can be changed by editing your  file like so:

gtk-font-name="Sans 14"

GNU Radio 3.8
The forthcoming GNU Radio 3.8 release has been updated to use GTK 3.0, which has native HiDPI support. To enable HiDPI support you can launch GRC like so:

$ GDK_SCALE=2 gnuradio-companion

You may find that you want to reduce the UI font size if it becomes too large in native HiDPI mode, you can do so following the instructions for 3.7 and specifying a smaller number.