Using the escape key closes some dialog panels, e.g. the city improvement list.
It does not close other dialogs, e.g. the introduction "book" display at start of game, the research display.
When there isn't a dialog active which the escape key will close, it brings up the options dialog.
The worst behaviour is seen when the research dialog is on display. Hitting <esc> closes that and brings up the options dialog.
Suggestion: Escape should always close the active dialog if there is one. If there is no active dialog it should do nothing. Use another key for the options dialog. This would be expected behaviour for many Windows users.
