@Override
	public int getSelectedColumnCount() {
		if (selectionModel != null) {
			int iMin = selectionModel.getMinSelectionIndex();
			int iMax = selectionModel.getMaxSelectionIndex();
			int count = 0;

			for (int i = iMin; i <= iMax; i++) {
				if (selectionModel.isSelectedIndex(i)) {
					count++;
				}
			}
			return count;
		}
		return 0;
	}
This returns all columns known by this model, both visible and not seen.
@return all columns known by this model, both visible and not seen.
Ghidra/Framework/Docking/src/main/java/docking/widgets/table/GTableColumnModel.java