public TreeColumn overColumn(int x) {
		if (x >= 0 && !mColumns.isEmpty()) {
			int divider = getColumnDividerWidth();
			int count = mColumns.size() - 1;
			int pos = 0;
			for (int i = 0; i < count; i++) {
				TreeColumn column = mColumns.get(i);
				pos += column.getWidth() + divider;
				if (x < pos) {
					return column;
				}
			}
			return mColumns.get(count);
		}
		return null;
	}