Wondering what the line with a blue dot on each end is in a popover window (in layout mode)?
Do you mean this
You can manually change the Angle (in Inspector), or drag the blue circle (or blue square) to change how the gradient is shown. You can drag the circle/square up and down, left and right and it's not just the Angle that gets changed!
Gradients are pretty cool, but may take some testing to get how you want.
* FileMaker Pro 16 Help (Filling objects, layout parts, or the layout background with a color gradient)
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