Hey Nexus-6, Thanks for working on this!
I have tried to compile the version you provided (the master branch of https://github.com/nexus6-haiku/Weather)
but this failed for me. Here is the log : )
I am using 64bit haiku on hrev56194+7
~/proj/Weather make
mkdir -p objects.x86_64-cc11-debug; \
mkdepend -ISource/ -Iobjects.x86_64-cc11-debug/ -p .cpp:objects.x86_64-cc11-debug/%n.o -m -f "objects.x86_64-cc11-debug/Util.d" Source/Util.cpp
mkdir -p objects.x86_64-cc11-debug; \
mkdepend -ISource/ -Iobjects.x86_64-cc11-debug/ -p .cpp:objects.x86_64-cc11-debug/%n.o -m -f "objects.x86_64-cc11-debug/CitiesListSelectionWindow.d" Source/CitiesListSelectionWindow.cpp
mkdir -p objects.x86_64-cc11-debug; \
mkdepend -ISource/ -Iobjects.x86_64-cc11-debug/ -p .cpp:objects.x86_64-cc11-debug/%n.o -m -f "objects.x86_64-cc11-debug/ForecastDeskbarView.d" Source/ForecastDeskbarView.cpp
mkdir -p objects.x86_64-cc11-debug; \
mkdepend -ISource/ -Iobjects.x86_64-cc11-debug/ -p .cpp:objects.x86_64-cc11-debug/%n.o -m -f "objects.x86_64-cc11-debug/ForecastView.d" Source/ForecastView.cpp
mkdir -p objects.x86_64-cc11-debug; \
mkdepend -ISource/ -Iobjects.x86_64-cc11-debug/ -p .cpp:objects.x86_64-cc11-debug/%n.o -m -f "objects.x86_64-cc11-debug/ForecastDayView.d" Source/ForecastDayView.cpp
mkdir -p objects.x86_64-cc11-debug; \
mkdepend -ISource/ -Iobjects.x86_64-cc11-debug/ -p .cpp:objects.x86_64-cc11-debug/%n.o -m -f "objects.x86_64-cc11-debug/SelectionWindow.d" Source/SelectionWindow.cpp
mkdir -p objects.x86_64-cc11-debug; \
mkdepend -ISource/ -Iobjects.x86_64-cc11-debug/ -p .cpp:objects.x86_64-cc11-debug/%n.o -m -f "objects.x86_64-cc11-debug/PreferencesWindow.d" Source/PreferencesWindow.cpp
mkdir -p objects.x86_64-cc11-debug; \
mkdepend -ISource/ -Iobjects.x86_64-cc11-debug/ -p .cpp:objects.x86_64-cc11-debug/%n.o -m -f "objects.x86_64-cc11-debug/MainWindow.d" Source/MainWindow.cpp
mkdir -p objects.x86_64-cc11-debug; \
mkdepend -ISource/ -Iobjects.x86_64-cc11-debug/ -p .cpp:objects.x86_64-cc11-debug/%n.o -m -f "objects.x86_64-cc11-debug/WSOpenMeteo.d" Source/WSOpenMeteo.cpp
mkdir -p objects.x86_64-cc11-debug; \
mkdepend -ISource/ -Iobjects.x86_64-cc11-debug/ -p .cpp:objects.x86_64-cc11-debug/%n.o -m -f "objects.x86_64-cc11-debug/LabelView.d" Source/LabelView.cpp
mkdir -p objects.x86_64-cc11-debug; \
mkdepend -ISource/ -Iobjects.x86_64-cc11-debug/ -p .cpp:objects.x86_64-cc11-debug/%n.o -m -f "objects.x86_64-cc11-debug/App.d" Source/App.cpp
g++ -c Source/App.cpp -iquote./ -iquoteSource/ -iquoteobjects.x86_64-cc11-debug/ -isystem/system/develop/headers/private/shared -isystem/system/develop/headers/private/interface -isystem/system/develop/headers/private/netservices -O0 -g -DLIBNETAPI_DEPRECATED -o "objects.x86_64-cc11-debug/App.o"
g++ -c Source/LabelView.cpp -iquote./ -iquoteSource/ -iquoteobjects.x86_64-cc11-debug/ -isystem/system/develop/headers/private/shared -isystem/system/develop/headers/private/interface -isystem/system/develop/headers/private/netservices -O0 -g -DLIBNETAPI_DEPRECATED -o "objects.x86_64-cc11-debug/LabelView.o"
g++ -c Source/WSOpenMeteo.cpp -iquote./ -iquoteSource/ -iquoteobjects.x86_64-cc11-debug/ -isystem/system/develop/headers/private/shared -isystem/system/develop/headers/private/interface -isystem/system/develop/headers/private/netservices -O0 -g -DLIBNETAPI_DEPRECATED -o "objects.x86_64-cc11-debug/WSOpenMeteo.o"
g++ -c Source/MainWindow.cpp -iquote./ -iquoteSource/ -iquoteobjects.x86_64-cc11-debug/ -isystem/system/develop/headers/private/shared -isystem/system/develop/headers/private/interface -isystem/system/develop/headers/private/netservices -O0 -g -DLIBNETAPI_DEPRECATED -o "objects.x86_64-cc11-debug/MainWindow.o"
g++ -c Source/PreferencesWindow.cpp -iquote./ -iquoteSource/ -iquoteobjects.x86_64-cc11-debug/ -isystem/system/develop/headers/private/shared -isystem/system/develop/headers/private/interface -isystem/system/develop/headers/private/netservices -O0 -g -DLIBNETAPI_DEPRECATED -o "objects.x86_64-cc11-debug/PreferencesWindow.o"
g++ -c Source/SelectionWindow.cpp -iquote./ -iquoteSource/ -iquoteobjects.x86_64-cc11-debug/ -isystem/system/develop/headers/private/shared -isystem/system/develop/headers/private/interface -isystem/system/develop/headers/private/netservices -O0 -g -DLIBNETAPI_DEPRECATED -o "objects.x86_64-cc11-debug/SelectionWindow.o"
g++ -c Source/ForecastDayView.cpp -iquote./ -iquoteSource/ -iquoteobjects.x86_64-cc11-debug/ -isystem/system/develop/headers/private/shared -isystem/system/develop/headers/private/interface -isystem/system/develop/headers/private/netservices -O0 -g -DLIBNETAPI_DEPRECATED -o "objects.x86_64-cc11-debug/ForecastDayView.o"
g++ -c Source/ForecastView.cpp -iquote./ -iquoteSource/ -iquoteobjects.x86_64-cc11-debug/ -isystem/system/develop/headers/private/shared -isystem/system/develop/headers/private/interface -isystem/system/develop/headers/private/netservices -O0 -g -DLIBNETAPI_DEPRECATED -o "objects.x86_64-cc11-debug/ForecastView.o"
g++ -c Source/ForecastDeskbarView.cpp -iquote./ -iquoteSource/ -iquoteobjects.x86_64-cc11-debug/ -isystem/system/develop/headers/private/shared -isystem/system/develop/headers/private/interface -isystem/system/develop/headers/private/netservices -O0 -g -DLIBNETAPI_DEPRECATED -o "objects.x86_64-cc11-debug/ForecastDeskbarView.o"
g++ -c Source/CitiesListSelectionWindow.cpp -iquote./ -iquoteSource/ -iquoteobjects.x86_64-cc11-debug/ -isystem/system/develop/headers/private/shared -isystem/system/develop/headers/private/interface -isystem/system/develop/headers/private/netservices -O0 -g -DLIBNETAPI_DEPRECATED -o "objects.x86_64-cc11-debug/CitiesListSelectionWindow.o"
g++ -c Source/Util.cpp -iquote./ -iquoteSource/ -iquoteobjects.x86_64-cc11-debug/ -isystem/system/develop/headers/private/shared -isystem/system/develop/headers/private/interface -isystem/system/develop/headers/private/netservices -O0 -g -DLIBNETAPI_DEPRECATED -o "objects.x86_64-cc11-debug/Util.o"
cat Source/Weather.rdef | cc -E -iquote./ -iquoteSource/ -iquoteobjects.x86_64-cc11-debug/ -isystem/system/develop/headers/private/shared -isystem/system/develop/headers/private/interface -isystem/system/develop/headers/private/netservices -O0 -g -DLIBNETAPI_DEPRECATED - | grep -av '^#' | rc -I Source/ -o "objects.x86_64-cc11-debug/Weather.rsrc" -
cc -o "objects.x86_64-cc11-debug/Weather" objects.x86_64-cc11-debug/App.o objects.x86_64-cc11-debug/LabelView.o objects.x86_64-cc11-debug/WSOpenMeteo.o objects.x86_64-cc11-debug/WSOpenMeteo.o objects.x86_64-cc11-debug/MainWindow.o objects.x86_64-cc11-debug/PreferencesWindow.o objects.x86_64-cc11-debug/SelectionWindow.o objects.x86_64-cc11-debug/ForecastDayView.o objects.x86_64-cc11-debug/ForecastView.o objects.x86_64-cc11-debug/ForecastDeskbarView.o objects.x86_64-cc11-debug/CitiesListSelectionWindow.o objects.x86_64-cc11-debug/Util.o -g -Xlinker -soname=_APP_ -LSource/ -Lobjects.x86_64-cc11-debug/ -lbe -lbnetapi -llocalestub -lshared -ltranslation -lstdc++ -lsupc++
/boot/system/develop/tools/bin/../lib/gcc/x86_64-unknown-haiku/11.2.0/../../../../x86_64-unknown-haiku/bin/ld: objects.x86_64-cc11-debug/WSOpenMeteo.o: in function `WSOpenMeteo::WSOpenMeteo(BHandler*, RequestType)':
/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:21: multiple definition of `WSOpenMeteo::WSOpenMeteo(BHandler*, RequestType)'; objects.x86_64-cc11-debug/WSOpenMeteo.o:/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:21: first defined here
/boot/system/develop/tools/bin/../lib/gcc/x86_64-unknown-haiku/11.2.0/../../../../x86_64-unknown-haiku/bin/ld: objects.x86_64-cc11-debug/WSOpenMeteo.o: in function `WSOpenMeteo::WSOpenMeteo(BHandler*, RequestType)':
/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:21: multiple definition of `WSOpenMeteo::WSOpenMeteo(BHandler*, RequestType)'; objects.x86_64-cc11-debug/WSOpenMeteo.o:/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:21: first defined here
/boot/system/develop/tools/bin/../lib/gcc/x86_64-unknown-haiku/11.2.0/../../../../x86_64-unknown-haiku/bin/ld: objects.x86_64-cc11-debug/WSOpenMeteo.o: in function `WSOpenMeteo::~WSOpenMeteo()':
/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:30: multiple definition of `WSOpenMeteo::~WSOpenMeteo()'; objects.x86_64-cc11-debug/WSOpenMeteo.o:/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:30: first defined here
/boot/system/develop/tools/bin/../lib/gcc/x86_64-unknown-haiku/11.2.0/../../../../x86_64-unknown-haiku/bin/ld: objects.x86_64-cc11-debug/WSOpenMeteo.o: in function `WSOpenMeteo::~WSOpenMeteo()':
/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:30: multiple definition of `WSOpenMeteo::~WSOpenMeteo()'; objects.x86_64-cc11-debug/WSOpenMeteo.o:/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:30: first defined here
/boot/system/develop/tools/bin/../lib/gcc/x86_64-unknown-haiku/11.2.0/../../../../x86_64-unknown-haiku/bin/ld: objects.x86_64-cc11-debug/WSOpenMeteo.o: in function `WSOpenMeteo::~WSOpenMeteo()':
/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:30: multiple definition of `WSOpenMeteo::~WSOpenMeteo()'; objects.x86_64-cc11-debug/WSOpenMeteo.o:/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:30: first defined here
/boot/system/develop/tools/bin/../lib/gcc/x86_64-unknown-haiku/11.2.0/../../../../x86_64-unknown-haiku/bin/ld: objects.x86_64-cc11-debug/WSOpenMeteo.o: in function `WSOpenMeteo::ResponseStarted(BUrlRequest*)':
/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:37: multiple definition of `WSOpenMeteo::ResponseStarted(BUrlRequest*)'; objects.x86_64-cc11-debug/WSOpenMeteo.o:/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:37: first defined here
/boot/system/develop/tools/bin/../lib/gcc/x86_64-unknown-haiku/11.2.0/../../../../x86_64-unknown-haiku/bin/ld: objects.x86_64-cc11-debug/WSOpenMeteo.o: in function `WSOpenMeteo::DataReceived(BUrlRequest*, char const*, long, long)':
/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:43: multiple definition of `WSOpenMeteo::DataReceived(BUrlRequest*, char const*, long, long)'; objects.x86_64-cc11-debug/WSOpenMeteo.o:/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:43: first defined here
/boot/system/develop/tools/bin/../lib/gcc/x86_64-unknown-haiku/11.2.0/../../../../x86_64-unknown-haiku/bin/ld: objects.x86_64-cc11-debug/WSOpenMeteo.o: in function `WSOpenMeteo::RequestCompleted(BUrlRequest*, bool)':
/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:52: multiple definition of `WSOpenMeteo::RequestCompleted(BUrlRequest*, bool)'; objects.x86_64-cc11-debug/WSOpenMeteo.o:/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:52: first defined here
/boot/system/develop/tools/bin/../lib/gcc/x86_64-unknown-haiku/11.2.0/../../../../x86_64-unknown-haiku/bin/ld: objects.x86_64-cc11-debug/WSOpenMeteo.o: in function `WSOpenMeteo::_ProcessWeatherData(bool)':
/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:81: multiple definition of `WSOpenMeteo::_ProcessWeatherData(bool)'; objects.x86_64-cc11-debug/WSOpenMeteo.o:/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:81: first defined here
/boot/system/develop/tools/bin/../lib/gcc/x86_64-unknown-haiku/11.2.0/../../../../x86_64-unknown-haiku/bin/ld: objects.x86_64-cc11-debug/WSOpenMeteo.o: in function `WSOpenMeteo::_ProcessCityData(bool)':
/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:300: multiple definition of `WSOpenMeteo::_ProcessCityData(bool)'; objects.x86_64-cc11-debug/WSOpenMeteo.o:/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:300: first defined here
/boot/system/develop/tools/bin/../lib/gcc/x86_64-unknown-haiku/11.2.0/../../../../x86_64-unknown-haiku/bin/ld: objects.x86_64-cc11-debug/WSOpenMeteo.o: in function `std::string __gnu_cxx::__to_xstring<std::string, char>(int (*)(char*, unsigned long, char const*, __va_list_tag*), unsigned long, char const*, ...)':
/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:62: multiple definition of `WSOpenMeteo::GetUrl(double, double)'; objects.x86_64-cc11-debug/WSOpenMeteo.o:/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:62: first defined here
/boot/system/develop/tools/bin/../lib/gcc/x86_64-unknown-haiku/11.2.0/../../../../x86_64-unknown-haiku/bin/ld: objects.x86_64-cc11-debug/WSOpenMeteo.o: in function `WSOpenMeteo::SerializeBMessage(BMessage*, BString)':
/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:285: multiple definition of `WSOpenMeteo::SerializeBMessage(BMessage*, BString)'; objects.x86_64-cc11-debug/WSOpenMeteo.o:/boot/home/proj/Weather/Source/WSOpenMeteo.cpp:285: first defined here
collect2: error: ld returned 1 exit status
/boot/system/develop/etc/makefile-engine:249: recipe for target 'objects.x86_64-cc11-debug/Weather' failed
make: *** [objects.x86_64-cc11-debug/Weather] Error 1