Extensive window management and multi-monitor management.
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Pro A lot of settings for every window or sub-window that opens
Pro Each window keeps its own position at startup/open
Pro Allows different wallpapers/screensavers for each monitor
While Windows limits your customization to 1 wallpaper and 1 screensaver, which has limitations for certain applications. For example, if your monitors have different resolutions or aspect ratios, wallpapers don't always play nice. Display Fusion lets you have a different wallpaper for each monitor which alleviates issues like this.
In industrial applications, this means that you could have a customer-facing monitor which has a different (more professional) wallpaper and screensaver.
Pro $25 for a lifetime upgrades
Pro Shortcuts for window management
Using keyboard shortcuts, you can lock your mouse to the confines of an area (a window, or even a specific monitor - useful for gaming), as well as resizing or moving the window. These are great additions to the window shortcuts built into Windows (alt+tab, Alt+F4, Win + D, etc).
Pro Windows snap to each other
Especially on large monitors, you may want to have multiple windows open on the same screen. Windows only snaps 2 windows to a screen, but Display Fusion snaps windows to the edge of other windows.
Con Not nearly as useful for single monitor setups
Most of the features are useful for multi-monitor setups. If you are just using one monitor, you won't be using the majority of the features available in Display Fusion.
Con Window splitting configuration requires manual input
The GUI for window splitting can be a bit tedious to work with - while it offers great customizability, it does require either calculating how many pixels you'd like, or trying it hit-and-miss if you'd like to i.e. fit an IM program with the contact list to a side of the screen. In other words - no real-time preview, and the splits' edges don't travel together when adjusting edges around.
Con Expensive for what it offers
Starting at $25, this program won't offer much utility to most users - however it can be useful for niche users. $5 or even $10 would be an easier pill to swallow.