Schematic or PCB window pops to front on mouseover in Linux dual monitor setup

Description

Issue #4099 (closed) was marked "fixed" a long time ago during version 5, but the fix was Windows-specific. That bug, or one with seemingly identical symptoms, is still a problem in my Linux installation, and still a problem in version 6.0.2.

I am using a dual monitor setup, and have only been able to reproduce the bug on the dual monitor machine, but I am not convinced it is really caused by the dual monitor setup. It happens even between windows on the same monitor.

Current behaviour: the schematic editor becomes the top window and steals focus whenever the mouse pointer touches it. UPDATE: When I first reported this I said it stole focus from other software or from other KiCAD modules. On further testing, I no longer think it steals focus from other KiCAD modules (for instance, schematic editor stealing from PCB editor); it seems to only steal focus from non-KiCAD software (for instance, schematic editor stealing focus from a Web browser). However, it's not only the schematic editor; at least the PCB editor also does it.

Expected behaviour: that does not happen.

Steps to reproduce

1. Open the schematic editor
2. Open some other software
3. Move the mouse pointer over the schematic editor window

KiCad Version

Application: KiCad

Version: 6.0.2, release build

Libraries:
	wxWidgets 3.1.4
	libcurl/7.77.0 OpenSSL/1.1.1j zlib/1.2.11 brotli/1.0.9 zstd/1.5.0 c-ares/1.17.1 libidn2/2.3.1 libpsl/0.21.1 (+libidn2/2.3.0) libssh2/1.9.0 nghttp2/1.43.0 OpenLDAP/2.4.59

Platform: Linux 4.19.59 x86_64, 64 bit, Little endian, wxGTK, , tty

Build Info:
	Date: Apr 30 2022 12:49:06
	wxWidgets: 3.1.4 (wchar_t,wx containers) GTK+ 3.24
	Boost: 1.75.0
	OCC: 7.6.2
	Curl: 7.75.0
	ngspice: 26
	Compiler: GCC 10.2.0 with C++ ABI 1014

Build settings:
	KICAD_USE_OCC=ON
	KICAD_SPICE=ON