Further segfault bug fixes in FListView

ChangeLog

@@ -2,6 +2,9 @@
 	* Use the Singleton design pattern to get a single object instance 
 	  via FTerm
 
+2019-05-26  Marek Habersack <grendel@twistedcode.net>
+	* Fix a segfault when processing input to empty FListView
+
 2019-05-17  Markus Gans  <guru.mail@muenster.de>
 	* Move system calls to the new class FSystem
 

src/flistview.cpp

@@ -2035,7 +2035,7 @@ void FListView::mouseHeaderClicked()
 //----------------------------------------------------------------------
 void FListView::wheelUp (int pagesize)
 {
-  if ( current_iter.getPosition() == 0 )
+  if ( itemlist.empty() || current_iter.getPosition() == 0 )
     return;
 
   if ( first_visible_line.getPosition() >= pagesize )
@@ -2059,6 +2059,9 @@ void FListView::wheelUp (int pagesize)
 //----------------------------------------------------------------------
 void FListView::wheelDown (int pagesize)
 {
+  if ( itemlist.empty() )
+    return;
+
   int element_count = int(getCount());
 
   if ( current_iter.getPosition() + 1 == element_count )
@@ -2181,6 +2184,9 @@ FObject::FObjectIterator FListView::appendItem (FListViewItem* item)
 //----------------------------------------------------------------------
 void FListView::processClick()
 {
+  if ( itemlist.empty() )
+    return;
+
   emitCallback("clicked");
 }
 
@@ -2290,6 +2296,9 @@ inline void FListView::keyRight (int& first_line_position_before)
 //----------------------------------------------------------------------
 inline void FListView::keyHome()
 {
+  if ( itemlist.empty() )
+    return;
+
   current_iter -= current_iter.getPosition();
   int difference = first_visible_line.getPosition();
   first_visible_line -= difference;
@@ -2299,6 +2308,9 @@ inline void FListView::keyHome()
 //----------------------------------------------------------------------
 inline void FListView::keyEnd()
 {
+  if ( itemlist.empty() )
+    return;
+
   int element_count = int(getCount());
   current_iter += element_count - current_iter.getPosition() - 1;
   int difference = element_count - last_visible_line.getPosition() - 1;
@@ -2352,6 +2364,9 @@ void FListView::setRelativePosition (int ry)
 //----------------------------------------------------------------------
 void FListView::stepForward()
 {
+  if ( itemlist.empty() )
+    return;
+
   if ( current_iter == last_visible_line )
   {
     ++last_visible_line;
@@ -2371,6 +2386,9 @@ void FListView::stepForward()
 //----------------------------------------------------------------------
 void FListView::stepBackward()
 {
+  if ( itemlist.empty() )
+    return;
+
   if ( current_iter == first_visible_line
     && current_iter != itemlist.begin() )
   {
@@ -2385,6 +2403,9 @@ void FListView::stepBackward()
 //----------------------------------------------------------------------
 void FListView::stepForward (int distance)
 {
+  if ( itemlist.empty() )
+    return;
+
   int element_count = int(getCount());
 
   if ( current_iter.getPosition() + 1 == element_count )
@@ -2418,7 +2439,7 @@ void FListView::stepForward (int distance)
 //----------------------------------------------------------------------
 void FListView::stepBackward (int distance)
 {
-  if ( current_iter.getPosition() == 0 )
+  if ( itemlist.empty() || current_iter.getPosition() == 0 )
     return;
 
   if ( current_iter.getPosition() - distance >= 0 )