The default visual style for runtime widgets and controls is defined by the currently applied Theme.
Selecting a Theme
Use the theme Selector in the Layout properties :
The background settings are inherited from the currently selected Theme.
This can be overridden by using the Background button in the Layout properties :
Inherit from theme (default)
The background style is defined by the currently selected Theme.
Un-select this option to allow to customize the following options.
The Background Color can be configured manually using a color picker :
Instead of a plain background color, you can use an image as background.
Click on the pen icon to select a file.
Even when configuring a different background color for the dashboard canvas, the Widgets’ background is still inherited from the Theme.
This is in order to maximize readability.
However, you may select Transparent Widgets to use the custom background (color or image) as widget background too :