This is the standard behavior of Gnome Dash to Dock and Dash to Panel, and it is also available on Windows (registry setting) and through Latte Dock. 

Currently, if you left-click on icon that represents more than one window (grouped windows), you are presented with full-screen overview of all the windows. This is bad for a couple reasons:

- The windows overview suffers from an issue wherein the thumbnails are hard to see due to the darkening effect. This makes the overview virtually unusable, at least for me. https://bugs.kde.org/show_bug.cgi?id=385522
- After clicking on an group icon, you have to move your mouse to a totally different area of the screen. This could be a huge distance, especially for touchpads.

I therefore propose adding click to cycle-grouped as an option, preferably by default. This behavior is both more efficient and more standard than the current one. 

So to get to the second window in a group you'd just have to single-click (if a window in the group is already active) or double-click. Much faster than the current behavior.