How to bend the rectangle on the left to the circle on the right? I've tried creating a circle and applying the "pattern along path" effect, but it only results in one color.
Seemingly no flood of answers "how to do it exactly and as a single operation". While waiting for one I write the workaround I know.
Three rectangles which wait for bending on a circle
Duplicate the rectangles (=select all, press Ctrl+D). Combine the parts of the duplicate by applying Path > Combine. It becomes single color. I removed the fill and inserted a black stroke to show it's a combined path. Copy the result to the clipboard to make it available in phase 4.
Insert to the circle path effect Pattern along path and set the pattern to be taken from the clipboard. Select effect mode single stretched. You must adjust manually the width of the bent shape.
Apply Path > Object to path and Path > Break apart to make the parts free. Set the right strokes (=none in this case) and pick with the eyedropper fill colors from the original (=1).
Current Inkscape seemingly converts circles, rectangles etc. preset shapes automatically to paths (=Bezier curves) when one attempts path operations. Path > Combine seemingly allows the pattern even to be a group.
There are still cases when the automatic conversion doesn't happen. An example: Extension > Generate from path > Interpolate. In such cases one must apply Path > Object to path to make the wanted thing possible.