Customizing the Look and Feel

Instead of rolling out hardcoded styles or reinvent the wheel, PyDM leverages the existing Qt Style Sheet mechanism.

Qt Style Sheet terminology and syntactic rules are almost identical to those of HTML CSS. More on the rules, selectors and syntax can be found at this link.

By default PyDM ships with a default stylesheet file that is used unless an user specify a file to be used either via the PyDM launcher argument –-stylesheet STYLESHEET or via the PYDM_STYLESHEET environment variable.

To help users extend this feature, PyDM offers two main configurations that can be used:


Path to the QSS files defining the global stylesheets for the PyDM application. When used, it will override the default look. If using multiple files they must be separated by the path separator. E.g.: /path_to/my_style_1.qss:/path_to/other/my_other_style.qss


Whether or not to include the PyDM Default stylesheet along with customized files. Note that the PyDM default stylesheet will have lower precedence compared to files specified at PYDM_STYLESHEET

Processing Order of Style Sheets

The file will be processed from top to bottom and the bottom-most rules will take precedence over rules defined at the top in case of repeated/conflicts.

Rules defined at widgets will always take precedence over general rules defined at higher levels.

Important Notes

When writing your own style sheet rules please be always mindful about your selectors since, as with HTML CSS, the style rules will cascade to child widgets.