NOTE: I know this can be done with the taskbar on the bottom. I seek the solution for a taskbar on the side.
I attached a picture of what I mean. In the screenshots, you can see that my taskbar program icons are arranged in a single column. I want to be able to have multiple columns. This would mean arranging the icons into squares and have them be placed side by side, as well as above and below one another.
This can be accomplished with taskbar being on the bottom of the screen, however, I require this arrangement when I have my taskbar on the side of my screen. Currently if I expand the taskbar horizontally, it only stretches out the icons horizontally rather than turn them into small squares to make room for side by side and placement of icons.
Additional icons that I add to my current taskbar are only accessible by using the horizontal scroll bar that appears at the bottom of the taskbar when there is no more space to accommodate any more icons.
Best Answer
Okay - I kind of found a way to do this, but it does not work with the taskbar vertical (or I haven't got it to work yet, pretty sure it won't anyways with this method).
A while back I wanted to get my icons centered like a Macs, so I followed this tutorial. It works perfect, and your taskbar stays centered that way (minus when you open new windows, they show up to the right of center). Your taskar should look similar to this:
After you have finished that tutorial, instead of locking the taskbar, drag it up one more space so it is two units high. After that, take the little scroll thing on the notification area side and drag that over until your icons are stacked like you want them, similar to this
Alternatively, you could add another folder on the other side of your icons and use that to adjust the stacking of the icons instead of the notification area, incase you like it in a certain way.
Now, if you want a vertical taskbar with programs or files, first unlock the taskbar and drag it to the side of the screen you would like for it to be on. Second, create some folders, that contain the items that you want to be stacked on the bar. For example, I just used Folder and then duplicated it to get Folder2 (that's why the two columns match) - unfortunately, I haven't found out how to make the taskbar icons multi layered yet (You can put an application in the folder, and it will launch, but it will then show up as the last icon in the task bar, and won't actually be a taskbar icon - I hope that makes sense.) I'll post back here if I can find a way to fix that - but anyways, this is what mine looked like.