ROSS RAMSEY Every modern Texas governor knows — or learns the hard way — that special legislative sessions are political minefields. And yet, they are tempted. In a regular session, lawmakers can file legislation on anything under the sun. In a special session, the governor writes the agenda, and anything that’s not on it is out of bounds. Regular sessions take place according to a constitutional calendar, whether a governor wants lawmakers in Austin or not. Special sessions only take place at the call of the governor. Calling a special session with a governor’s own agenda is a power move. But it’s packed with risk.