fnConvert = function(vPx) {
				return vPx / iAvailableWidth * 100;
			}
Checks if the column is allowed to be displayed with a width smaller then
the minimal required by <code>FlexibleColumnLayout.COLUMN_MIN_WIDTH</code>.

This is needed only during interactive resize, when a column can temporarily
have a smaller width while the user drags and before the user releases the mouse.
@param {"begin"|"mid"|"end"} sColumn the column name
@returns {boolean} the flag