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 $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.
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.
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 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 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.