Issue with window title bar icons

Description of the Issue

The issue is when N++ window is maximized on the secondary screen that is pivoted (1440x2560). The same window on the primary screen behaves OK.
The three title bar icons (minimize, restore, close) on the top-right corner of the window do not behave as expected.
Sometimes they get "transparent" in a way that N++ window does not react, but the clicks are sent to the window underneath it - e.g. hitting close icon closes the window below N++'s one.
The "sometimes" is defined as when the mouse pointer touches the top or right edge of the screen (remember the window is maximized) - then every few pixels hovering mouse of the buttons turn the highlight on and off.

Steps to Reproduce the Issue

1. Start Windows Notepad,
2. Move Windows Notepad window to the secondary screen and maximize its window.
3. Start N++ (Not sure is matters - I always run it as an Administrator).
4. Move N++ window to the secondary screen and maximize its window.
5. Move your mouse to the top right corner of the screen.
6. Hover over the windows' system icons while the mouse pointer touches the top or right edge of the screen. The highlight of buttons changes on and off. When not-highlighted then the window underneath N++ will get the click (e.g. close app)
7. When the mouse is in the very corner of the screen the close icon is not highlighted. Click it.
8. N++ windows stays up, but the Windows Notepad window gets closed.

Expected Behavior

Well, when clicking N++ close button I'd love not to close the underlying window but N++ window rather.

Actual Behavior

Clicking on window's system icons do not affect N++ window but the window below.

Debug Information

Notepad++ v7.8.7 (64-bit)
Build time : Jun 5 2020 - 02:38:56
Path : C:\Program Files\Notepad++\notepad++.exe
Admin mode : ON
Local Conf mode : OFF
OS Name : Windows 10 Enterprise (64-bit)
OS Version : 1909
OS Build : 18363.900
Current ANSI codepage : 65001
Plugins : DSpellCheck.dll HTMLTag.dll mimeTools.dll nppConverter.dll NppExport.dll NPPJSONViewer.dll NppSaveAsAdmin.dll NppXmlTreeviewPlugin.dll PreviewHTML.dll XMLTools.dll _CustomizeToolbar.dll

Reproduce the issue using the listed Windows 10, rotated secondary-display setup and the numbered steps; no source file or test is named in the report. Trace the title-bar button hit testing and maximized-window behavior, then verify that clicks in the screen corner consistently act on the N++ window rather than the window underneath.