try dmd app.d -I/home/osboxes/Downloads/build/dwt/imp -J/home/osboxes/Downloads/build/dwt/org.eclipse.swt.gtk.linux.x86/res -L-L/home/osboxes/Downloads/build/dwt/lib -L-lorg.eclipse.swt.gtk.linux.x86 -L-ldwt-base ...