It must be obvious, but how do I import a custom .svg file so it is accessible in the icon list that can be added to a button?
There is a little "+" button on the bottom of the icons list that allows you to add files to the icons pack for that file.
You have to create a layout object that takes an SVG icon, then click the + icon in the lower left corner below the existing icons and choose your svg file. This will add the svg icon to the library of the current file - you can delete the layout object you added in order to be able to add the icon, and the icon will still remain in the library.
You also need to make sure that your svg file is compatible with FileMaker SVG icons - though that's another topic. You'll get an error message if it isn't.
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