Yesterday I summarized the good and bad of Safari 4’s new approach to tabs. It’s clear from the many comments in the discussion thread for that article that people have strong opinions, pro and con, about Safari 4’s interface. But there’s no denying that by replacing the title bar with the tab bar the way Apple did, the company has made selecting and moving Safari windows more difficult and less intuitive than before.

But my goal here isn’t to revisit that discussion; if you want all the details, check out yesterday’s article. Instead, I’m using today’s Mac Gems column to revisit one of my favorite past Gems, MondoMouse…which just so happens to offer an excellent alternative for selecting, moving, and resizing Safari 4 windows, as well as windows in any other program.

With MondoMouse installed, if you can see any part of a window, you can identify, select, move, or resize it. Via a new MondoMouse pane in System Preferences, you choose modifier keys for each of these actions. (I personally have shift+control set to display information about a window, option+command set to move a window, control+option set to resize a window, and control+option+command set to select a window.) You perform any of these actions by simply moving your mouse cursor over the desired window—anywhere on or in that window—and then holding down the appropriate modifiers.

The select mode simply selects the window, bringing it forward, just as if you’d clicked anywhere in it; it’s similar to the “cursor focusing” feature available on some Unix variants. (You have the option to switch to a window by simply moving the mouse cursor over it—no modifier keys required—but I find this approach to be frustrating: it’s too easy to accidentally switch to a window you didn’t mean to.) The information mode simply displays the window name and the program to which the window belongs—useful if most of the window is hidden behind others.

But my favorite modes are move and resize. If you hold down your move modifiers, moving the cursor actually moves the window just as if you’d dragged the window by the title bar—even if the title bar, or even most of the window, is hidden. Similarly, holding down your resize modifiers while moving the mouse resizes the window, even if the resize handle at the lower-right corner of the window is hidden. Even better, you’re not forced to resize only down and to the right; whichever corner your cursor is closest to becomes the “resize corner.” (You can disable this feature if you prefer to resize only from the bottom-right corner.) A nice touch: If the window you’re working with is in the background, behind other windows, it remains there after moving or resizing it.

One other benefit of these features is that if you ever encounter a window that’s partly offscreen, you can easily move it in situations where you’d normally be stuck, and you can resize it without having to first move the window so that the lower-right corner is visible.

Since I covered version 1.1 of MondoMouse back in 2006, it’s received a good number of updates that have included some useful new features. For example, the aforementioned ability to resize windows from the corner closest to the mouse, rather than just the lower-right corner. When moving or resizing a window, MondoMouse also now displays a highlighted border to indicate the edges of the window, even if some of those edges are hidden behind other windows; and if a window can’t, for whatever reason, be resized, its border will be highlighted red. Finally, if a particular program doesn’t get along with MondoMouse (see below), you can specifically exclude it.

One feature I’d like to see is the capability to assign MondoMouse actions to modified mouse clicks instead of just movements. This would allow you to assign the select, identify, move, and resize actions to buttons on multi-button mice. Another great potential feature, although it’s likely beyond the developer’s control, is the capability to assign these modes to multitouch gestures on Apple’s latest laptop trackpads. For example, I’d love to be able to move a window by dragging with multiple fingers!

One limitation of MondoMouse is that it has trouble resizing windows for programs that use older window types. The number of affected programs is getting smaller every day, but there are still a few out there.

Unfortunately, MondoMouse is one of those utilities that’s tough to appreciate until you actually see it in use; I encourage you to give it a try. It’s been one of my favorite OS X add-ons for the past few years; I use it so often I sometimes forget it isn’t part of Leopard. Now that I’m using Safari 4 Beta to surf the Web, MondoMouse is even more useful. With some people speculating that Safari 4’s new window interface may find its way into more OS X programs, MondoMouse just may become one of your must-have Gems.