Reduce SessionItem signaling

• reduce SessionItem signaling regarding sample items
• cleanup/simplify code
• fix warning

GUI/Model/Sample/ParticleLayoutItem.cpp

@@ -21,24 +21,13 @@
 #include "GUI/Model/Sample/ParticleItem.h"
 #include "GUI/Model/Types/DoubleDescriptor.h"
 
-namespace {
-
-const QString density_tooltip =
-    "Number of particles per square nanometer (particle surface density).\n "
-    "Should be defined for disordered and 1d-ordered particle collections.";
-const QString weight_tooltip =
-    "Weight of this particle layout.\n"
-    "Should be used when multiple layouts define different domains in the sample.";
-
-} // namespace
-
 ParticleLayoutItem::ParticleLayoutItem() : SessionItem(M_TYPE)
 {
     setToolTip("A layout of particles");
 
-    addProperty(P_TOTAL_DENSITY, 0.01)->setToolTip(density_tooltip);
+    addProperty(P_TOTAL_DENSITY, 0.01);
     getItem(P_TOTAL_DENSITY)->setDecimals(10);
-    addProperty(P_WEIGHT, 1.0)->setToolTip(weight_tooltip);
+    addProperty(P_WEIGHT, 1.0);
 
     registerTag(T_PARTICLES, 0, -1,
                 {ParticleItem::M_TYPE, ParticleCoreShellItem::M_TYPE,
@@ -85,10 +74,12 @@ double ParticleLayoutItem::totalDensity() const
     }
 }
 
-
 DoubleDescriptor ParticleLayoutItem::weight() const
 {
-    return DoubleDescriptor(getItem(P_WEIGHT), Unit::unitless);
+    DoubleDescriptor d(getItem(P_WEIGHT), Unit::unitless);
+    d.tooltip = "Weight of this particle layout.\n"
+                "Should be used when multiple layouts define different domains in the sample.";
+    return d;
 }
 
 QVector<ItemWithParticles*> ParticleLayoutItem::particles() const