Resizing

Shapes and many symbols are freely resizable: select the object and drag the handles — the size snaps to whole centimetres and the dimensions appear live on the object. Alternatively, enter width and depth exactly in the properties panel. Furniture with fixed sizes (e.g. your chairs and tables) always keeps its real dimensions.

Try it out

Place shapes or symbols from the left column and drag the handles:

This demo is the real editor — the exact same behaviour as in your plan.