Can the toolbar be made vertical in a desktop app?
only if you roll your own
Shame really, as most screens are wider than they are tall.
Just use a Listbox. It is quite easy to do.
So then how does that help? If a screen is wider than it is tall and you run a toolbar on the side, the mouse has to travel further to get to a tool?
never though about using a listbox as a vertical toolbar
The only thing the Listbox offers is the automatic position management. With all the weird things about Listbox, I’d personally rather just do it in a Canvas.
Depending on how you measure, the travel would be easier and would feel faster. I’d say Fitt’s could even go deeper, but since these are toolbars it may be exempt from the “infinite targets” Fitts defines.
Is you have square buttons then the target area is the same and what matters is how easy it is to get to them. For mouse users horizontal movement is faster and more accurate than vertical movement, so a vertical toolbar would be faster to get close to (quick pivot on the elbow) and easier to hit (fine-movement is also easier horizontally). For trackpads it’s moot because acceleration in touchpads takes the direction of quick swipes into account and accelerates proportionally and accordingly.
if you have rectangular buttons in your toolbar then having a vertical toolbar also is better because the horizontal target is wider and aligned with the direction you’re moving the cursor.
Automatic position, isolation of events and you have a paint event where you can do everything you’d do in a canvas but in discrete regions rather than a shared one.
If there was scrolling involved I would agree with you, since listboxes don’t know how to really scroll the way the concept is understood today (that is, smooth pixel-level scrolling) but for something like a toolbar in vertical mode they’d be like a specially-optimized canvas. I only see advantages 
Not quite. It offers you pretty much the same drawing abilities as a canvas, automatic scrolling and CellClick etc, events to react to, a row tag or cell tag to store objects, etc.
What weirdness are you experienceing?
Uses less screenspace.
I remember someone who, when using Word, insisted on having all possible toolbars visible at the top of the window. Consequently she had very little space available for the actual text being composed. Meanwhile, over to the right, a chunk of desktop was visible where the toolbars, arranged vertically, could have gone.
Technically the left hand side is known as the Source Bar and not a tool bar, ideally it’s for navigation purposes. Otherwise you’re shifting standard paradigms; which can and sometimes does work, but it will confuse some users.