A sort of "key" to what this whole zoom thing (Ctl+Mousewheel) is about may be had from the fact that:
it works in Microsoft Word,
it works in Microsoft Excel,
it even works in my DeLorme Highway Map program that is so old nobody had thought about having a wheel on a mouse when it came out,
it works in most, but not all, web pages in IE
on my main machine.

I'll note incidentally, that it doesn't just change the type size, it "zooms" the whole screen in "normal" programs.

A second thing to note is that this particular feature is NOT documented in help files for Win95, Win98, Win2K, or WinXP. ALL of these say "See the documentation for your mouse for additional information."

If you just plug a mouse with a wheel into your machine, the PNP (Plug and Play) feature in Windows should detect that the mouse has a wheel, and the zoom feature will probably work in most programs that enable it (and most programs should enable this feature) using the Windows default mouse driver. The only use for the wheel that is documented in Windows Help is for scrolling, and you can go to Control Panel - Mouse and change things like how many lines one "step" on the "scroll wheel" advances the page.

Most "mouse kits" come with a small program disk though, that includes a driver specific to the mouse. IF you install the "device specific driver" that comes with the mouse, you may or may not find a number of "extra features" are available. The only place where any "extra features" are likely to be documented will be on the disk that comes with the mouse. Some mouse installation programs may put a "mouse help" file on the machine, but it's not too common.

You can have more than one mouse installed at the same time, if you really want to confuse yourself. Each mouse can have its own device specific driver with different features. A mouse can have up to 7 (the most I've seen) BUTTONS and up to 3 WHEELS (again, I haven't seen one with more wheels than that, but they may exist). "MousePads" used with some CAD programs may have 30 or more buttons, and more exotic devices.

The current "standard" mouse is probably the one with two buttons and one wheel. The wheel may be rotated to scroll or may be pushed to "click." Earlier wheel mouse devices may not have the "wheel click" switch. The usual function of the "wheel click" is to place an "anchor" on the screen. When you "click" the wheel by pressing it down, a "splat" appears on the screen. If you move the mouse up or down from the "splat," the screen scrolls at a speed roughly proportional to how far you move away from the marker. A second wheel "click" removes the anchor.

Any action that a Windows compliant program can perform can be assigned to any input from any I/O device as a "shortcut." MOST actions that are assignable appear in one of the menus in most programs; but there are a whole bunch of others that require a little more exotic "command line." If you go into Tools - Macros in most Windows programs you can find a list of functions sufficient to confuse nearly any of us. Any function that appears there can be "put on a toolbar" or "in a menu listing" in nearly any Windows program. (IE is an exception, and is not set up for you to mess with the menus and toolbars.)

Any "special function" your mouse performs in a given program is most likely just a "quick key" assignment, built into the driver for that mouse. Since you can set the same "shortcut keys" to do different things in different programs, what happens is pretty much up to the person who "assigned" the device signals to the functions that person wanted - or "knew" you would want. IF there are any "unconventional" assignments, they should be documented on the disk that came with your mouse. Unfortunately, things you may not know about, that the "programmer" thought were "standard functions," may be ignored in the documentation; but usually there's at least some help there. The documentation for your mouse may tell you how to change what the buttons and wheel do, if you want to do so.

You can, in effect, change the size of stuff on your screen in Control Panel - Display by changing the screen resolution. If you haven't looked there, you may be able to get something you like better; but the settings that work will depend on what your monitor can do. Many laptops (with LCD displays) insist on a particular resolution, and won't let you change - especially to a higher resolution. Except in very rare circumstances NO PROGRAM should ever change the screen resolution you set here. I have seen a very few "Flash" sites that ask to change your resolution to suit their pages. They should open a new window at the resolution they want you to use, they should not change to a setting your monitor can't handle, and should revert to what you have set when you close that window. (They don't always do what they should.)

In the same Control Panel - Display area, you can set whether you want large, medium, or small type and icons. If you use a high screen resolution, you likely will want to kick the sizes up a little.

Nearly all Windows compliant programs offer a zoom setting, under View on the top toolbar. Internet Explorer is an exception, since there is no zoom available on the View menu. There is also no Format section on the IE toolbar, which is where you normally would change font sizes, and no Macro section under Tools to permit you to change the items on the menus and toolbars. This does not mean that the omitted functions won't work; but for some fairly obvious reasons you're not supposed to "work them" just by clicking - or mess with the toolbars.

If your mouse implements a zoom, or a font-size change, it may work in IE, and should on a "compliant" html page. If the page designer has used "exotic" methods in setting up the page, the zoom function may not work. ["Nothing is idiot proof, because idiots are too damned clever."] Since whether it works depends on the page that's posted, you can't change it. If you can't FIX IT, it's not a PROBLEM. It's a "situation" you should ACCOMODATE or IGNORE.

Those who actually feel a need for this mousewheel zoom should perhaps be aware that in WinXP, and possibly in some earlier versions, in Start - Programs - Accessories -Accessibility there is a "Magnifier" that presents a very much enlarged view in a small inset window. As implemented, it's marginally useful; and there are specialized programs you should look at if you really need this kind of help. But it's there. If you want to use it to try it out, I'd suggest putting a shortcut on your desktop so you can turn it on and off easily.

John