Because DarkBasic Professional is a complete programming language it incorporates features such as time elapsed (dbTimer()), string functions (dbVal(), dbLen()), and file commands(dbReadString(), dbOpenToRead()).
Because PureGDK wraps the engine for use with another language, these features are expected to already exist and are therefore redundant and nonessential to the functionality of the engine.
For C++, dbTimer is replaced by clock() (see time.h) or GetTickCount() (see Windows.h/MSDN). There is an example of GetTickCount() in PureGDK examples "animation-1", "basic3d-1", and "matrix-2".
File operations are handled with either ifstream, ofstream, fopen, fread, fwrite, etc; or Win32 equivalents.
Quote: "There is a problem: how to swap windows when game is running? Maybe better to use HWND_TOP instead HWND_TOPMOST ? (in debug & release mode too)"
The example provided in the help file is just an example. You can customize it however you like. For example, I use main() while debugging so that I can use the console window for debugging output and only set it to WinMain() for release.