SteamVR: Cursor and laser pointer do not line up correctly on Desktop mirroring mode when changing display's custom scaling size to 125.

[KWS-Compat]

When the user set a custom scaling value of 125 for the main display, using Desktop mirroring mode within SteamVR will show that the cursor on the desktop and the laster pointer do not line up correctly.

Repro Steps:

1. Right-click anywhere on Windows Desktop.
2. Navigate to the 'Display settings' tab.
3. Select 'Advanced scaling settings' under Scale and layout section.
4. Set custom scaling to 125.
5. Sign out from Windows 10 and sign in again.
6. Launch SteamVR.
7. Open SteamVR Overlay, select Desktop option. Observe that when the user move the laser pointer anywhere on the desktop, the cursor and and the laser pointer do not line up correctly.

Note:

• Other custom scaling values (150, 200) were also tested but the issue only occurs on custom scaling value of 125.
• When the user change the scaling value to 125 using non-custom value under 'Change the size of text, apps ,and other items' section, the issue does not occur. (see attachment)

Expected Result: The cursor and laser pointer to line up correctly regardless of the DPI value. Actual Result: The cursor and laser pointer do not line up correctly.

Repro Rate: 5/5

Tested Config: The issue does not appear to be hardware-related. CPU: AMD Ryzen 5 1500X, Intel i5-8600K GPU: Nvidia GTX 1080 Ti, Nvidia GTX 1080 HMD: WMR, HTC Vive

Build: Windows 10 Pro (Version 1809 | OS Build 17763.292) SteamVR Beta Build 1.2.10

[KWS-Compat]

Issue has been observed to no longer occur as of SteamVR Beta Version 1.3.18.