RE:longterm investor with TVIAbusive "takeunders" or as i call them "f***overs" such as you describe are unusual in Canada because of minority shareholder right laws, but they have happened (they are many jurisdictions in the world with much weaker protections, including certain US states such as Indiana). Usually, the worst thing one need fear in Canada is a zero-premium or low-premium offer made at a time when the share price is in the doldrums. In the case of TVI, there are too many of us minority investors who know what the company is truly worth, and we would fight tooth and nail against any abuse.
The best thing you can do if you fear such a thing is to mainitain a stink bid for milliions of shares at or a bit below the current high bid. This way, if a scoundrel tries to drive the share price down for a few days before announcing a takeover offer, you wll pick up some cheap shares AND the wall of shares will stymie the attempt to drive the market price down. Such a stink bid might also happen to benefit you in the absence of takeover shenanigans if some other poor investor suffers a calamitous margin call and is forced to sell sell sell. This is definitely a smart use of margin if you have it and are not otherwise putting it to use.