Changes after upgrade

[Greybeard ZR-1]

I have a Mac desktop, version 10.6.8. Recently, seemingly after a routine upgrade, the behavior of the mouse and keyboard have changed.
I used to be able to use the mouse to drag the side marker, the blue indicator, down the edge of the page to scroll the page. Now, this can only be accomplished by clicking on the arrow indicators instead, or using the arrows on the keyboard. It still works, but not as usable or convenient.
Is this because of the "upgrade" that was just accomplished? Or have I changed it inadvertently by other means?

Sorry if I'm not using the correct terminology, I'm fairly ignorant, computer wise.

TIA.

 

[bobtomay]

You can still grab the indicator and slide if you first begin the scroll - while the indicator is showing, you can grab it with the mouse/trackpad to use it.

New feature which I am sure is more useful on notebooks with trackpads than it is with a desktop/mouse combo.

You can change when/how the scroll bars appear in:
System Preferences - General