Fix poor detection of a dupe instance

[eugenesvk]

Old FindWindow() function could mistake an Explorer folder 'UI for ETW'
for another instance of 'UI for ETW' (since window title is identical)
New custom function registers a unique window message that allows to
uniquely identify another instance of 'UI for ETW'
Bonus: restore the minimized window of 'UI for ETW'

Resolves: #147

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[randomascii]

It looks basically good but I'll need the cla/google signed before I can accept the patch.

[eugenesvk]

@googlebot I signed it!

[randomascii]

I get four instances of this error when compiling:

1>C:\src\github\UIforETW\UIforETW\Settings.cpp(17,10): fatal error C1853: 'x64\Release\UIforETW_devrel.pch' precompiled header file is from a different version of the compiler, or the precompiled header is C++ and you are using it from C (or vice versa)

I don't mind switching to C++17 but I don't think that global constructors are a great idea. How about:

int GetAreYouMeId() {
static const UINT uwmAreYouMe = RegisterWindowMessage(L"678fd291e05741edb987c0a4f5650866");
return uwmAreYouMe;
}

Then it gets constructed on first use instead of before WinMain

[randomascii]

The return type in my sample function should be UINT.

[randomascii]

I noticed this was still open and decided to see why. Part of the reason is that I pasted the wrong error message into my last comment. The actual error message is:

1>C:\src\github\UIforETW\UIforETW\UIforETW.h(46,19): error C7525: inline variables require at least '/std:c++17' (compiling source file Settings.cpp)

That message happens on this line:

inline const UINT uwmAreYouMe = RegisterWindowMessage(L"678fd291e05741edb987c0a4f5650866");

I continue to think that that isn't a great idea. Inline data is great. Global constructors that run before main are not.