hello all. i have an imac that somehow has had a setting changed somewhere. i am relatively new to macs, so thanks in advance for your patience (i am running OSX 10.5.8). my optical mouse no longer highlights text, it just grabs the entire window and moves it around. it will not grab the "slider bar" on the edges of windows either, it just moves the whole window. i have gone into settings and look through the mouse options and cannot find anything. i apologize if this is a silly question; i am a windows guy who is confused by the simplicity of this machine! thanks!