KOTOR: Protect against a division by zero in WidgetListBox

If the listbox items have a height of zero (or no defined height at
all), calculating the number of widget would provoke a division by
zero.

This fixes Coverity Scan issue #1391035.

src/engines/kotor/gui/widgets/listbox.cpp

@@ -74,15 +74,18 @@ void WidgetListBox::setPermanentHighlightEnabled(bool value) {
 	_permanentHighlightEnabled = value;
 }
 
-const std::vector<KotORWidget *> &WidgetListBox::createItemWidgets(int count) {
+const std::vector<KotORWidget *> &WidgetListBox::createItemWidgets(uint count) {
 	if (!_protoItem)
 		throw Common::Exception("ListBox widget has no PROTOITEM");
 
-	int widgetCount = count > 0 ? count :
-			getHeight() / _protoItem->getStruct("EXTENT").getSint("HEIGHT");
+	const int64 itemHeight = _protoItem->getStruct("EXTENT").getSint("HEIGHT");
 
-	for (int i = 0; i < widgetCount; ++i) {
-		Common::UString name = Common::UString::format("%s_ITEM_%d", _tag.c_str(), i);
+	uint widgetCount = count;
+	if ((count == 0) && (itemHeight > 0))
+		widgetCount = getHeight() / itemHeight;
+
+	for (uint i = 0; i < widgetCount; ++i) {
+		Common::UString name = Common::UString::format("%s_ITEM_%u", _tag.c_str(), i);
 		createItem(name);
 	}
 

src/engines/kotor/gui/widgets/listbox.h

@@ -44,7 +44,7 @@ class WidgetListBox : public KotORWidget {
 	 *  @param count number of items to add or 0 to add maximum number of
 	 *               items that fit into the listbox
 	 */
-	const std::vector<KotORWidget *> &createItemWidgets(int count = 0);
+	const std::vector<KotORWidget *> &createItemWidgets(uint count = 0);
 
 	void addItem(const Common::UString &text);
 	void refreshItemWidgets();