The Consumer Preview of Windows 8 had a number of rough edges in its user interface, and Microsoft promised to address at least some of them in the Release Preview. The most prominent unpleasantness with the Consumer Preview was the handling of multimonitor systems, and specifically the interaction with the hot corners. The work done for the Release Preview makes the experience better, but some concerns remain.

To recap briefly: the Start screen is invoked by clicking in the bottom-left corner of the screen, the app switcher by moving the mouse to either left-hand corner and then vertically toward the center of the screen, and the charms by moving to either right-hand corner and then vertically toward the center of the screen.

In the Consumer Preview, only the corners of the "primary" screen—the one with the Start screen—were hot. However, in multimonitor settings, this made those corners very difficult to hit: the mouse cursor had to be positioned on the exact corner, without slipping over into the adjacent screen.

The Release Preview makes some alterations to this system. First, every screen corner is now hot; switching between apps, invoking the charms, or visiting the Start screen can be done from any monitor. Second, it has six-pixel corner traps on the screen edges, so that if the cursor is in the hot spot, it can't so easily slip out: pushing the mouse in the direction of the hot spot leaves it trapped.

While extensive use of the Release Preview has not yet been possible, it's clear that these changes are a step in the right direction. The corner traps make it easier to get the mouse into the right spot in the corner. They're not so large that they'll trip up the cursor during deliberate movements between screens; they're just enough to make the corners a little more forgiving. Getting to the hotspot is still going to be easer on a single-screen system, but it's no longer the exercise in frustration that it was in the Consumer Preview.

However, that's only addressing half the problem. The vertical movements used by the task switcher and charms bar are still troublesome. Consider two screens side-by-side. The cursor is on the left-hand screen, and the user wishes to invoke the charms bar. The easiest way to do this is to push the mouse up, to the top of the screen (where the screen edge forms a natural barrier) and then right, to the corner.

The trap will stop the cursor falling onto the right-hand screen, so progress has been made relative to the Consumer Preview. But then the problem: when moving the cursor down, if the mouse has any rightward momentum at all, it will still be enough to carry the cursor into the next screen, preventing the charms from appearing. The vertical edge doesn't extend more than six pixels from the corner, so unless the mouse movement is straight down, with not even a hint of left or right motion, the charms or task switcher won't appear. Single monitor users, in contrast, can continue to push the mouse right, to keep the cursor glued against the screen edge.

As a result, while single-screen users can make an easy, continuous, sweeping gesture to invoke these features, multimonitor users will still have to take some care.

The decision to make all corners hot has its pros and cons, too. It certainly reduces the amount of mousing around that is required, and that is certainly convenient. But some of the behavior is a little disconcerting. Again, consider two screens side-by-side. The left-hand screen is running a Metro-style application, and the mouse is on the right-hand screen. If you bring up the Start screen on that right-hand screen, the Metro-style application on the left-hand screen will disappear. Dismiss the Start screen, and the Metro-style application will not reappear. You'll have to poke through the task switcher to get it back.

The Metro environment is fundamentally single-screen. All Metro-style applications, including the Start screen itself (though it is not quite an application), have to reside on the same screen. It doesn't matter so much which screen, and you can freely switch, but it has to be the same screen. If you move the Start screen, by invoking it on a different monitor, then every Metro-style application will be moved alongside.

Where this gets even stranger is when you have two Metro-style applications visible; one snapped to the screen edge, the other occupying the remainder of the space. Invoking the Start screen on a different monitor will hide both, but when you dismiss the Start screen, the snapped application will be displayed once more. Only the full-size one will be hidden.

And this effect is only something that happens when you bring up the Start screen on a different monitor; bring it up on the same monitor as your pair of applications, and the normal, expected behavior occurs. The Start screen hides both apps, but upon dismissing it, both are made visible again.

In the Consumer Preview, you could put the cursor at the top edge of a Metro-style app and it would turn into a hand. This allowed you to "pick up" the application and do one of two things: drag it off the bottom of the screen to quit it, or drag it to the edge of the screen to make it do the 320 pixel-wide snap thing. In the Release Preview there is a third option: you can drag it to a different screen. As soon as the cursor hits another screen, the app that you're dragging around will be dropped, and it will display on the new screen. And when you do this in snapped view, with two apps visible, moving one to a different screen will drag the other one along with it, again underscoring Metro's essentially single-screen nature.

On top of all this, I have had some issues with the corner traps not actually kicking in. I don't know if it's a Windows problem or a VMware issue or what. VMware Workstation 8 supports multiple monitors in the virtual machine. These are "real" monitors: each shows up as a different device in Device Manager, each gets its own taskbar, and each gets its own set of hot corners. But due to some quirk, either in VMware or Windows 8 or both, those different monitors aren't getting the corner traps. If I run Windows 8 on bare metal, the traps appear correctly; in the virtual machine, they do not.

All in all, Windows 8 Release Preview gives a better experience on multimonitor systems, but it's still quite rough. On single monitor systems, the only real difficulty is getting the gestures for the charms and task switcher down pat. Once you have these, the user interface works consistently. On multimonitor systems, there will still be missed gestures that require you to stop and think about what you're doing. The multimonitor experience is less fluid, less predictable, and simply worse than the single-screen equivalent.