Why Do Overlays Look Blurry on a Second Monitor? (DPI Mixing)

A multi-monitor setup where the monitors have different DPI scaling settings — for example, a 4K monitor at 150% scaling paired with a 1080p monitor at 100% scaling — produces a characteristic problem on Windows: some applications render sharply on one monitor and blurrily on the other. The blurriness is most visible on overlays, small floating windows, and Electron-based apps. The cause is the application's DPI awareness level, which determines how Windows scales the app's window when it crosses monitors with different DPIs. This guide covers what per-monitor DPI awareness is, why Electron apps are particularly affected, and what the user can do about it.

For neighbouring topics, see display disconnects that reset window positions, 4K screenshots blow past clipboard limits, clipboard tools on multi-monitor Windows setups, and ultrawide screens and modal clipboard popups. For a related topic, see HDR and wide-color screenshots on the clipboard.

What DPI scaling is

DPI (dots per inch) scaling is Windows' mechanism for keeping UI elements at a usable physical size on high-resolution displays. A 27-inch 4K monitor has a pixel density of about 163 pixels per inch, which is too dense for UI elements designed for 96 pixels per inch (the historical Windows default). At 100% scaling, text and icons on a 4K monitor would be tiny; at 150% scaling, Windows renders the UI at 1.5x, making elements the same physical size as on a 1080p monitor at 100%.

DPI scaling is configured per-monitor in Settings → System → Display → Scale. Each connected monitor can have its own scaling setting. Windows remembers the setting per monitor, so the configuration persists across reboots.

The scaling affects how applications render. An app that is "DPI aware" renders at the native resolution of each monitor, producing sharp text and crisp icons. An app that is not DPI aware is rendered at a base resolution and scaled up by Windows, producing blurriness on high-DPI monitors.

The three DPI awareness levels

Windows supports three levels of DPI awareness for applications:

• DPI unaware — the app renders at 96 DPI and is scaled by Windows. Sharp on a 100% scaling monitor; blurry on a 150% scaling monitor.
• System DPI aware — the app renders at the system's primary monitor DPI and is scaled when moved to other monitors. Sharp on the primary; blurry on monitors with a different DPI.
• Per-monitor DPI aware (v1 and v2) — the app renders at the native DPI of each monitor it appears on. Sharp on all monitors.

The "per-monitor v2" awareness is the modern standard, introduced in Windows 10 version 1703. It handles DPI changes when a window is dragged between monitors, when a monitor's scaling changes, and when a monitor is connected or disconnected.

An app's DPI awareness is declared in its manifest or set programmatically with the SetProcessDpiAwareness API. The declaration is per-app, not per-window.

Why Electron apps are affected

Electron is the application framework that powers many modern desktop apps, including VS Code, Slack, Discord, and Edge-Drop. Electron is built on Chromium, which is per-monitor v2 DPI aware in recent versions. In theory, an Electron app should render sharply on all monitors.

In practice, Electron apps have historically had DPI bugs. The most common symptom is a window that renders sharply on the primary monitor and blurrily on a secondary monitor with a different DPI. The cause is usually one of:

• The Electron version is old. Per-monitor v2 support was stabilised in Electron 5-7. Older versions may have partial or broken support.
• The app's main window is created before the DPI awareness is set. The window inherits the default awareness, which may not be per-monitor v2.
• The app uses a transparent frameless window. Transparency and frameless windows interact poorly with DPI scaling in some Electron versions, producing rendering artifacts on the secondary monitor.
• The app's GPU acceleration is disabled. Without GPU acceleration, the rendering path falls back to software, which may not handle DPI correctly.

A clipboard shelf built on Electron with a transparent frameless window — which is the Edge-Drop architecture — is in the highest-risk category for DPI bugs. The shelf may render sharply on the primary monitor and blurrily on the secondary.

Diagnosing the blurriness

To confirm that the blurriness is a DPI issue and not a different problem:

1. Set both monitors to the same scaling. In Settings → System → Display → Scale, set both monitors to 100% (or both to 150%). If the blurriness disappears, it was a DPI issue.
2. Check the app's DPI awareness. Right-click the app's executable, select Properties → Compatibility → Change high DPI settings, and look at the override options. If "Use this setting to fix scaling problems for this app instead of the one in Settings" is checked, the app is being forced to a specific awareness.
3. Look for the blur on the secondary monitor specifically. Move the app's window from the primary to the secondary monitor and observe whether the text becomes blurry. If it does, the app is not handling per-monitor DPI correctly.

What the user can do

The user's options are limited because DPI awareness is a developer-side configuration. The user cannot make an unaware app aware. The user can:

• Set both monitors to the same scaling. This eliminates the DPI difference and the blurriness. The cost is that one monitor's UI is the wrong physical size (too small on a 4K at 100%, too large on a 1080p at 150%).
• Set the app to "Override high DPI scaling behaviour" in Compatibility settings. This forces Windows to scale the app, which may or may not improve the rendering. The setting is in Properties → Compatibility → Change high DPI settings → Override high DPI scaling behavior → Scaling performed by: System. Try System and Application and see which looks better.
• Place the app on the primary monitor. If the app is system DPI aware, it renders sharply on the primary monitor. The user can keep the app on the primary and accept that it does not cross to the secondary.
• Update the app. Newer versions of Electron apps often fix DPI bugs. Check for updates and apply them.

For a clipboard shelf specifically, the option is to place the shelf on the monitor with the same DPI as the primary. If the primary is 4K at 150% and the secondary is 1080p at 100%, the shelf goes on the primary. The user gives up the convenience of having the shelf on the secondary, but the shelf renders sharply.

What the developer can do

Developers of Electron apps can fix DPI blurriness by:

• Upgrading Electron to a recent version (version 20 or later has stable per-monitor v2 support).
• Setting the DPI awareness in the main process before any windows are created: app.commandLine.appendSwitch('high-dpi-support', 'true').
• Declaring per-monitor v2 awareness in the manifest. This is the <application xmlns="urn:schemas-microsoft-com:asm.v3"><windowsSettings><dpiAwareness>PerMonitorV2</dpiAwareness></windowsSettings></application> block.
• Handling the display-metrics-changed event in Electron to re-render the window when the DPI changes.
• Testing on a mixed-DPI setup. A developer who only tests on a single DPI will not catch DPI bugs.

Edge-Drop declares per-monitor v2 awareness and uses Electron 34, which should handle mixed DPI correctly. If a user observes blurriness, the most likely cause is a graphics driver issue or a specific monitor configuration that the app does not handle. Reporting the bug to the app's issue tracker is the right path.

The 4K monitor at 150% case

The most common mixed-DPI setup in 2026 is a 4K primary monitor at 150% scaling paired with a 1080p or 1440p secondary at 100% scaling. This setup produces sharp rendering on the 4K and slightly blurry rendering on the secondary for apps that are system DPI aware but not per-monitor v2 aware.

For a clipboard shelf on the 4K monitor, the rendering is sharp. The shelf's text and icons are at native 4K resolution, scaled by Windows to 150%. The shelf looks correct.

For a clipboard shelf on the secondary, the rendering depends on the app's awareness. If the app is per-monitor v2 aware, the shelf renders at the secondary's native resolution (1080p or 1440p) at 100% scaling, which is sharp. If the app is system DPI aware, the shelf is rendered at 150% (the primary's scaling) and then scaled down to 100% by Windows, producing blurriness.

A short checklist

• Mixed-DPI multi-monitor setups can make some apps render blurrily on the secondary monitor.
• The cause is the app's DPI awareness level, which is a developer-side configuration.
• Electron apps with transparent frameless windows are at higher risk.
• The user can set both monitors to the same scaling, override the app's DPI behaviour, or place the app on the primary monitor.
• The developer can fix the issue by upgrading Electron, declaring per-monitor v2 awareness, and testing on mixed DPI.
• For a clipboard shelf, prefer the monitor with the same DPI as the primary if blurriness is observed.

Related reading

• 4K Screenshots Blow Past Clipboard Limits
• Gaming Fullscreen and Clipboard Hotkeys
• Clipboard Tools on Multi-Monitor Windows Setups
• Win+V Not Working on Windows 11: 9 Fixes

Sources

• Microsoft Learn — High DPI Desktop Application Development on Windows — official documentation for DPI awareness levels, including per-monitor v2 awareness
• Microsoft Learn — DPI awareness (manifest) — official documentation for declaring DPI awareness in the app manifest
• Electron — High DPI documentation — official Electron documentation for window creation, including the high-dpi-support command-line switch
• Microsoft Learn — SetProcessDpiAwarenessContext function — official documentation for the API developers use to set DPI awareness programmatically
• Microsoft Support — Fix apps that appear blurry on a secondary monitor — official troubleshooting guidance for the mixed-DPI blurriness problem

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