Fix #25: Program throws exception when clicking on the 'stylesheet' list if...

Fix #25: Program throws exception when clicking on the 'stylesheet' list if there are no stylesheets.

src/gui/control/gallery_list.hpp

@@ -37,6 +37,11 @@ class GalleryList : public wxPanel {
 	void select(size_t item, size_t subcol = NO_SELECTION, bool event = true);
 	/// Is there an item selected?
 	inline bool hasSelection(size_t subcol = 0) const { return subcolumns[subcol].selection < itemCount(); }
+	/// Get the id of the selected item, throws if there is no selection
+	inline size_t getSelectionId(size_t subcol = 0) const {
+		if (!hasSelection(subcol)) throw Error(_("No selection"));
+		return subcolumns[subcol].selection;
+	}
 	/// Is the given item selected?
 	inline bool isSelected(size_t item, size_t subcol = 0) const {
 		return subcol < subcolumns.size() && subcolumns[subcol].selection == item;

src/gui/control/package_list.hpp

@@ -39,7 +39,7 @@ class PackageList : public GalleryList {
 	 *  Throws if the selection is not of type T */
 	template <typename T>
 	intrusive_ptr<T> getSelection(bool load_fully = true) const {
-		intrusive_ptr<T> ret = dynamic_pointer_cast<T>(packages.at(subcolumns[0].selection).package);
+		intrusive_ptr<T> ret = dynamic_pointer_cast<T>(packages.at(getSelectionId()).package);
 		if (!ret) throw InternalError(_("PackageList: Selected package has the wrong type"));
 		if (load_fully) ret->loadFully();
 		return ret;

src/gui/new_window.cpp

@@ -90,6 +90,7 @@ void NewSetWindow::OnOK(wxCommandEvent&) {
 
 void NewSetWindow::done() {
 	try {
+		if (!stylesheet_list->hasSelection()) return;
 		StyleSheetP stylesheet = stylesheet_list->getSelection<StyleSheet>();
 		set = intrusive(new Set(stylesheet));
 		set->validate();