Assembly: Fix: Select datum should not show dragger. (#20051)

* Assembly: Fix: Select datum should not show dragger.

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* Update ViewProviderAssembly.cpp

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

src/Mod/Assembly/Gui/ViewProviderAssembly.cpp

@@ -642,6 +642,11 @@ bool ViewProviderAssembly::getSelectedObjectsWithinAssembly(bool addPreselection
                     // In case of sub-assembly, the jointgroup would trigger the dragger.
                     continue;
                 }
+                if (onlySolids
+                    && !(obj->isDerivedFrom<App::Part>() || obj->isDerivedFrom<Part::Feature>()
+                         || obj->isDerivedFrom<App::Link>())) {
+                    continue;
+                }
                 App::DocumentObject* part =
                     getMovingPartFromRef(assemblyPart, selRoot, subNamesStr);