Copy shown values to clipboard

It would be useful if there was an option to copy the shown value to clipboard once you click to exit from the selection mode for bounds, spacing, horizontal and vertical, by clicking with mouse.

Start by locating the selection-mode handling for bounds, spacing, horizontal, and vertical values, especially the mouse-click path that exits the mode. Trace where the shown values are produced and identify the application's clipboard entry point. Done means the selected value can be copied when selection mode is exited, with the behavior working for all four measurement types.

Written by the indexing model from the issue text.