I am looking for the settings to open the group of certain icons (there is a small arrow at the bottom right corner of the icon that we have to click if we want to see more functions as in sub category) . I just want to avoid the 'click' to open them. Is that possible to open automatically when mouse is on the icon ?
You're describing the function of how a "linked" toolbar works. Cascading out a linked toolbar requires a mouse click and hold.
It is not possible to cascade a linked toolbar without the click in Rhino.