Which is strange because any app that can operate on more than one document at the same time opens a separate window for each document on OS X. Even Photoshop. This works well on OS X because of how OS X manages applications. Let's for a moment consider GIMP if it was a native OS X application.
First, to switch between different applications, OS X just uses application switching whereas Windows and GNOME/KDE use window switching. IMO, window switching is a terrible design decision because it clutters the application switcher and the taskbar/dock and breaks operations that should logically apply to entire applications (quit, hide, Exposé etc.) Another desktop OS that uses application switching instead of window switching is Haiku (a BeOS descendant). Anyhow, if GIMP ran on OS X, you wouldn't need to sift through a bunch of separate windows when you wanted to focus on GIMP. You'd just switch to GIMP the application instead of separately bringing each of GIMPs eighty seven windows to the front first.
Second, when a document based application loses focus, OS X will hide all floating toolbars and panels and all you will see are your document windows. In Exposé, too, all floating panels and toolbars are hidden. This would mean GIMP's myriad tool windows would become invisible when you switched from the GIMP to another application, or when you viewed GIMP's windows in Exposé. No more needles visual clutter!
Third, OS X has a top menubar. This means each of GIMP's windows wouldn't need to have a separate menubar. The global menubar would enable and disable menu entries as you focused on different windows.
First, to switch between different applications, OS X just uses application switching whereas Windows and GNOME/KDE use window switching. IMO, window switching is a terrible design decision because it clutters the application switcher and the taskbar/dock and breaks operations that should logically apply to entire applications (quit, hide, Exposé etc.) Another desktop OS that uses application switching instead of window switching is Haiku (a BeOS descendant). Anyhow, if GIMP ran on OS X, you wouldn't need to sift through a bunch of separate windows when you wanted to focus on GIMP. You'd just switch to GIMP the application instead of separately bringing each of GIMPs eighty seven windows to the front first.
Second, when a document based application loses focus, OS X will hide all floating toolbars and panels and all you will see are your document windows. In Exposé, too, all floating panels and toolbars are hidden. This would mean GIMP's myriad tool windows would become invisible when you switched from the GIMP to another application, or when you viewed GIMP's windows in Exposé. No more needles visual clutter!
Third, OS X has a top menubar. This means each of GIMP's windows wouldn't need to have a separate menubar. The global menubar would enable and disable menu entries as you focused on different windows.