With PyQt, it is possible to use silx.gui widgets (and widgets written with PyQt in general) from the Qt Designer.
The following silx.gui widgets are available in the Qt Designer:
The following software must be installed:
The PYQTDESIGNERPATH environment variable defines the search paths for plugins enabling use of PyQt widgets in the designer.
To start the Qt Designer with silx.gui widgets available, on Linux, run the following from the command line:
PYQTDESIGNERPATH=<silx_designer_plugin_dir> designer
See Using Qt Designer in PyQt documentation.