App/Gui: improve expression binding of PropertyEnumeration

The enumeration items are exposed through sub path '.Enum'. When
'ShowAll' is enabled in property view, this sub path is exposed as a
sub property item named 'Enum', and can be either manually edited or
bound with an expression.

src/App/Enumeration.cpp

@@ -82,11 +82,9 @@ Enumeration::~Enumeration()
 void Enumeration::tearDown(void)
 {
     // Ugly...
-    char **plEnums = (char **)_EnumArray;
-
-    // Delete C Strings first
-    while (*plEnums != NULL) {
-        free(*(plEnums++));
+    for(char **plEnums = (char **)_EnumArray; *plEnums != NULL; ++plEnums) {
+        // Delete C Strings first
+        free(*plEnums);
     }
 
     delete [] _EnumArray;
@@ -98,6 +96,9 @@ void Enumeration::tearDown(void)
 
 void Enumeration::setEnums(const char **plEnums)
 {
+    if(plEnums == _EnumArray)
+        return;
+
     std::string oldValue;
     bool preserve = (isValid() && plEnums != NULL);
     if (preserve) {
@@ -118,7 +119,11 @@ void Enumeration::setEnums(const char **plEnums)
     findMaxVal();
 
     // set _index
-    _index = 0;
+    if (_index < 0)
+        _index = 0;
+    else if (_index > _maxVal)
+        _index = _maxVal;
+
     if (preserve) {
         setValue(oldValue);
     }
@@ -311,6 +316,10 @@ Enumeration & Enumeration::operator=(const Enumeration &other)
 
 bool Enumeration::operator==(const Enumeration &other) const
 {
+    if(_index != other._index)
+        return false;
+    if (getCStr() == other.getCStr())
+        return true;
     if (getCStr() == NULL || other.getCStr() == NULL) {
         return false;
     }