(As the result of the absolutely non-functioning search function I cannot find my original posts.)  

Using Sony CD Architect a bunch lately.  

I can grab the edges of the scroll gadget and can adjust the zoom.   

Double clicking the scroll gadget fits the project to the screen.  

Quick, easy, reasonable.   How can this be wrong?

Unless I'm misunderstanding, you can do the drag zoom the same way from the area between the two magnifying glasses on each scroll bar... As well as from cluck dragging up/down in the time Rucker where/when the pointer changes to a magnifying glass...

Shift-F will fit the project to the screen or at least as much as possible... Same as CD Architect which I use all the time too...

Keni

Yeah, it is a similar approach, Keni.   I've been using Vegas Studio a bit lately so I understand what the OP is referring to with the horizontal scroll bar widget.  
 
So even though it's not something essential for me since I'm used to the timeline gestures, I've voted anyway since it's not a bad idea to have that functionality in the scroll bar too.
 

What am I missing here?

I use CD Architect regularly... The zoom control is almost identical to the one in each scroll bar in Sonar...

In the lower right corner are three zoom controls. Two are buttons to zoom in/out per/click. The one in between the two magnifying glasses is a drag zoom almost the same as the Sony feature...

Is there something else I'm missing?

Keni

The scroll gadget can be grabbed and pulled on both ends. ;;;; edit ::   in the scroll bar, not the dudes in the corner.
Double clicking it fits the project to the window.
It is way quicker to find the scroll gadget than the itty bitty little boxes in the right corner of the screen.
 
And when SPlat is spread across both screens the scroll gadgets can be close to 30 inches away from where my eyes want to be focused.

Right, it's the same scroll bar widget you'd grab to move back and forth along the timeline.   I'm assuming CD Architect is the same as Vegas based on YDHTCMJ's description, but the widget itself has "stretch-points" along its outer edges for adjusting zoom level; i.e., the widget physically changes size as zoom level changes.
 

Interesting...
 
I've been using CD Architect since it was originally released and I find it a less comfortable set of tools for zooming.
 
Sonar has so many ways to do this that I get things done much faster...
 
I too am using a 30" screen with 2560 (?) resolution... Though only one... One of the true fixes in SPlat for me is the one for the Z+drag zoom command as it (usually - Lanes are still a pita) puts what I want to fill the window...
 
But other than that, the scroll bar icons seem large enough as I do not need to read them... I know what they do... and these days I use the timeline drag up/down zoom far more often...
 
Regarding zom. I just need a couple of things changed/fixed... The minimum/maximum lane heights need to be revised so they can be as can tracks!  ...and (preferably) displayed within the track space instead of below it... Or at least a way to disable the "promoted" clips image within the track space as it totally confused my eye as to which lane/track is which! ...along with wasting screen real estate!
 
Ooops... I'm ranting again... Sorry...
 
Keni

I find that you can hover the selector between the two delta characters and use the middle-wheel on my mouse to zoom in and out on either the horizontal or vertical axis.
 

Hi Steve...
 
Yes, I know that set of tools and though it's there I never felt that comfortable with it's results...
 
I wouldn't mind it being added to Sonar but personally I would prefer them to focus on issues with Lanes as they are my most uncomfortable issues with Sonar since the change from Layers... ;-)
 
Keni