If you build the KF5 version of umbrello, you'll end up with a broken desktop file. It calls umbrello in the Exec line, while the executable is actually named umbrello5. So starting it from the application menu doesn't work.
Git commit 54f5b361e0989e01baf768fbef70d483b2e785fa by Ralf Habacker. Committed on 23/06/2017 at 16:46. Pushed by habacker into branch 'Applications/17.04'. Fix 'org.kde.umbrello5.desktop has wrong Exec line'. FIXED-IN:2.22.3 (KDE Applications 17.04.3) M +1 -0 umbrello/CMakeLists.txt https://commits.kde.org/umbrello/54f5b361e0989e01baf768fbef70d483b2e785fa
Sorry, but that string replacement is too general. It also replaces umbrello with umbrello5 in the Icon= line (meaning the icon won't be found). I would suggest to use this instead: string(REPLACE "Exec=umbrello" "Exec=umbrello5" UMBRELLO_DESKTOP_OUT "${UMBRELLO_DESKTOP_OUT}")
Git commit efd2efb32f5d00c23c314e9c96615e00a679a29e by Ralf Habacker. Committed on 24/06/2017 at 07:35. Pushed by habacker into branch 'Applications/17.04'. Fixup of 'org.kde.umbrello5.desktop has wrong Exec line'. The former string replacement was too general. FIXED-IN:2.22.3 (KDE Applications 17.04.3) M +1 -1 umbrello/CMakeLists.txt https://commits.kde.org/umbrello/efd2efb32f5d00c23c314e9c96615e00a679a29e