diff --git a/aegisub/src/base_grid.cpp b/aegisub/src/base_grid.cpp
index 0b48e9e36..b861d86a2 100644
--- a/aegisub/src/base_grid.cpp
+++ b/aegisub/src/base_grid.cpp
@@ -100,6 +100,7 @@ BaseGrid::BaseGrid(wxWindow* parent, wxWindowID id, const wxPoint& pos, const wx
 /// @brief Destructor 
 ///
 BaseGrid::~BaseGrid() {
+	ClearMaps();
 	delete bmp;
 }
 
@@ -140,16 +141,16 @@ void BaseGrid::UpdateStyle() {
 
 /// @brief Clears grid 
 ///
-void BaseGrid::Clear () {
-	Selection lines_removed;
-	GetSelectedSet(lines_removed);
-	AnnounceSelectedSetChanged(Selection(), lines_removed);
+void BaseGrid::ClearMaps() {
+	Selection old_selection(selection);
 
-	diagMap.clear();
-	diagPtrMap.clear();
-	selMap.clear();
+	index_line_map.clear();
+	line_index_map.clear();
+	selection.clear();
 	yPos = 0;
 	AdjustScrollbar();
+
+	AnnounceSelectedSetChanged(Selection(), old_selection);
 }
 
 
@@ -211,34 +212,33 @@ void BaseGrid::MakeCellVisible(int row, int col,bool center) {
 /// @param select        
 ///
 void BaseGrid::SelectRow(int row, bool addToSelected, bool select) {
-	if (row < 0 || (size_t)row >= selMap.size()) return;
+	if (row < 0 || (size_t)row >= index_line_map.size()) return;
+
+	AssDialogue *line = index_line_map[row];
 
 	if (!addToSelected) {
-		// Sends change notifications for itself
-		ClearSelection();
+		Selection old_selection(selection);
+		selection.clear();
+		selection.insert(line);
+		AnnounceSelectedSetChanged(selection, old_selection);
 	}
 
-	if (select != !!selMap[row]) {
-		selMap[row] = select;
-		
-		if (!addToSelected) {
-			Refresh(false);
-		}
-		else {
-			int w = 0;
-			int h = 0;
-			GetClientSize(&w,&h);
-			RefreshRect(wxRect(0,(row+1-yPos)*lineHeight,w,lineHeight),false);
-		}
+	else if (select && selection.find(line) == selection.end()) {
+		selection.insert(line);
 
-		Selection lines_added;
-		Selection lines_removed;
-		if (select)
-			lines_added.insert(diagPtrMap[row]);
-		else
-			lines_removed.insert(diagPtrMap[row]);
+		Selection added;
+		added.insert(line);
 
-		AnnounceSelectedSetChanged(lines_added, lines_removed);
+		AnnounceSelectedSetChanged(added, Selection());
+	}
+
+	else if (!select && selection.find(line) != selection.end()) {
+		selection.erase(line);
+
+		Selection removed;
+		removed.insert(line);
+
+		AnnounceSelectedSetChanged(Selection(), removed);
 	}
 }
 
@@ -276,16 +276,11 @@ void BaseGrid::SelectVisible() {
 /// @brief Unselects all cells 
 ///
 void BaseGrid::ClearSelection() {
-	Selection lines_removed;
-	GetSelectedSet(lines_removed);
+	Selection old_selection(selection.begin(), selection.end());
 
-	int rows = selMap.size();
-	for (int i=0;i<rows;i++) {
-		selMap[i] = false;
-	}
-	Refresh(false);
+	selection.clear();
 
-	AnnounceSelectedSetChanged(Selection(), lines_removed);
+	AnnounceSelectedSetChanged(Selection(), old_selection);
 }
 
 
@@ -296,8 +291,9 @@ void BaseGrid::ClearSelection() {
 /// @return 
 ///
 bool BaseGrid::IsInSelection(int row, int) const {
-	if ((size_t)row >= selMap.size() || row < 0) return false;
-	return !!selMap[row];
+	if ((size_t)row >= index_line_map.size() || row < 0) return false;
+
+	return selection.find(index_line_map[row]) != selection.end();
 }
 
 
@@ -306,18 +302,27 @@ bool BaseGrid::IsInSelection(int row, int) const {
 /// @return 
 ///
 int BaseGrid::GetNumberSelection() const {
-	return std::count(selMap.begin(), selMap.end(), 1);
+	return selection.size();
 }
 
 
 
-/// @brief Gets first selected row 
-/// @return 
+/// @brief Gets first selected row index
+/// @return Row index of first selected row, -1 if no selection
 ///
 int BaseGrid::GetFirstSelRow() const {
-	std::vector<int>::const_iterator first = std::find(selMap.begin(), selMap.end(), 1);
-	if (first == selMap.end()) return -1;
-	return std::distance(selMap.begin(), first);
+	Selection::const_iterator it = selection.begin();
+
+	if (it == selection.end()) return -1;
+
+	int index = GetDialogueIndex(*it);
+
+	for (; it != selection.end(); ++it) {
+		int other_index = GetDialogueIndex(*it);
+		if (other_index < index) index = other_index;
+	}
+
+	return index;
 }
 
 
@@ -340,24 +345,25 @@ int BaseGrid::GetLastSelRow() const {
 /// @return Array with indices of selected lines
 ///
 wxArrayInt BaseGrid::GetSelection(bool *cont) const {
-	// Prepare
-	int nrows = GetRows();
 	int last = -1;
 	bool continuous = true;
-	wxArrayInt selections;
 
-	// Scan
-	for (int i=0;i<nrows;i++) {
-		if (selMap[i]) {
-			selections.Add(i);
-			if (last != -1 && i != last+1) continuous = false;
-			last = i;
-		}
+	std::set<int> sel_row_indices;
+
+	for (Selection::const_iterator it = selection.begin(); it != selection.end(); ++it) {
+		sel_row_indices.insert(GetDialogueIndex(*it));
+	}
+
+	// Iterating the int set yields a sorted list
+	wxArrayInt res;
+	for (std::set<int>::iterator it = sel_row_indices.begin(); it != sel_row_indices.end(); ++it) {
+		res.Add(*it);
+		if (last != -1 && *it != last+1) continuous = false;
+		last = *it;
 	}
 
-	// Return
 	if (cont) *cont = continuous;
-	return selections;
+	return res;
 }
 
 
@@ -366,7 +372,7 @@ wxArrayInt BaseGrid::GetSelection(bool *cont) const {
 /// @return 
 ///
 int BaseGrid::GetRows() const {
-	return diagMap.size();
+	return index_line_map.size();
 }
 
 
@@ -981,18 +987,24 @@ void BaseGrid::SetColumnWidths() {
 
 
 
-/// @brief Gets dialogue from map 
-/// @param n 
-/// @return 
+/// @brief Get dialogue by index
+/// @param n Index to look up
+/// @return Subtitle dialogue line for index, or 0 if invalid index
 ///
 AssDialogue *BaseGrid::GetDialogue(int n) const {
-	try {
-		if (n < 0 || (size_t)n >= diagMap.size()) return NULL;
-		return dynamic_cast<AssDialogue*>(*diagMap.at(n));
-	}
-	catch (...) {
-		return NULL;
-	}
+	if (n < 0 || n >= (int)index_line_map.size()) return 0;
+	return index_line_map[n];
+}
+
+
+
+/// @brief Get index by dialogue line
+/// @param diag Dialogue line to look up
+/// @return Subtitle index for object, or -1 if unknown subtitle
+int BaseGrid::GetDialogueIndex(AssDialogue *diag) const {
+	std::map<AssDialogue*,int>::const_iterator it = line_index_map.find(diag);
+	if (it != line_index_map.end()) return it->second;
+	else return -1;
 }
 
 
@@ -1015,37 +1027,17 @@ bool BaseGrid::IsDisplayed(AssDialogue *line) {
 /// @brief Update maps 
 ///
 void BaseGrid::UpdateMaps() {
-	// Store old
-	int len = selMap.size();
-	std::vector<AssDialogue *> tmpDiagPtrMap(diagPtrMap);
-	std::vector<int> tmpSelMap(selMap);
-
-	// Clear old
-	diagPtrMap.clear();
-	diagMap.clear();
-	selMap.clear();
+	index_line_map.clear();
+	line_index_map.clear();
 	
-	// Re-generate lines
 	for (entryIter cur=AssFile::top->Line.begin();cur != AssFile::top->Line.end();cur++) {
 		AssDialogue *curdiag = dynamic_cast<AssDialogue*>(*cur);
 		if (curdiag) {
-			// Find old pos
-			int sel = 0;
-			for (int i=0;i<len;i++) {
-				if (tmpDiagPtrMap[i] == curdiag) {
-					sel = tmpSelMap[i];
-					break;
-				}
-			}
-
-			// Add new
-			diagMap.push_back(cur);
-			diagPtrMap.push_back(curdiag);
-			selMap.push_back(sel);
+			line_index_map[curdiag] = (int)index_line_map.size();
+			index_line_map.push_back(curdiag);
 		}
 	}
 
-	// Refresh
 	Refresh(false);
 }
 
@@ -1211,12 +1203,14 @@ wxArrayInt BaseGrid::GetRangeArray(int n1,int n2) const {
 // SelectionController
 
 
-void BaseGrid::GetSelectedSet(Selection &selection) const {
-	for (size_t i = 0; i < selMap.size(); ++i) {
-		if (selMap[i] != 0) {
-			selection.insert(GetDialogue((int)i));
-		}
-	}
+void BaseGrid::GetSelectedSet(Selection &os) const {
+	os.insert(selection.begin(), selection.end());
 }
 
 
+void BaseGrid::SetSelectedSet(const Selection &new_selection) {
+	Selection old_selection(selection);
+	selection = new_selection;
+	AnnounceSelectedSetChanged(new_selection, old_selection);
+}
+
diff --git a/aegisub/src/base_grid.h b/aegisub/src/base_grid.h
index 3b7f149ed..1158a8df0 100644
--- a/aegisub/src/base_grid.h
+++ b/aegisub/src/base_grid.h
@@ -105,6 +105,10 @@ private:
 
 	void DrawImage(wxDC &dc);
 
+	Selection selection;
+	std::vector<AssDialogue*> index_line_map;
+	std::map<AssDialogue*,int> line_index_map;
+
 protected:
 
 	/// DOCME
@@ -124,14 +128,11 @@ protected:
 	/// DOCME
 	int yPos;
 
-	/// DOCME
-	std::vector<int> selMap;
-
 public:
 	// SelectionController implementation
 	virtual void SetActiveLine(AssDialogue *new_line) { }
 	virtual AssDialogue * GetActiveLine() const { return 0; }
-	virtual void SetSelectedSet(const Selection &new_selection) { }
+	virtual void SetSelectedSet(const Selection &new_selection);
 	virtual void GetSelectedSet(Selection &selection) const;
 	virtual void NextLine() { }
 	virtual void PrevLine() { }
@@ -145,12 +146,6 @@ public:
 	/// DOCME
 	bool byFrame;
 
-	/// DOCME
-	std::vector<entryIter> diagMap;
-
-	/// DOCME
-	std::vector<AssDialogue *> diagPtrMap;
-
 	void AdjustScrollbar();
 	void SetColumnWidths();
 	void BeginBatch();
@@ -167,7 +162,7 @@ public:
 	void SelectVisible();
 	wxArrayInt GetSelection(bool *continuous=NULL) const;
 
-	void Clear();
+	void ClearMaps();
 	void UpdateMaps();
 	void UpdateStyle();
 
@@ -176,6 +171,7 @@ public:
 	void MakeCellVisible(int row, int col,bool center=true);
 
 	AssDialogue *GetDialogue(int n) const;
+	int GetDialogueIndex(AssDialogue *diag) const;
 
 	BaseGrid(wxWindow* parent, wxWindowID id, const wxPoint& pos = wxDefaultPosition, const wxSize& size = wxDefaultSize, long style = wxWANTS_CHARS, const wxString& name = wxPanelNameStr);
 	~BaseGrid();
diff --git a/aegisub/src/dialog_styling_assistant.cpp b/aegisub/src/dialog_styling_assistant.cpp
index 8670006a5..bea4e987e 100644
--- a/aegisub/src/dialog_styling_assistant.cpp
+++ b/aegisub/src/dialog_styling_assistant.cpp
@@ -274,8 +274,7 @@ void DialogStyling::OnActivate(wxActivateEvent &event) {
 	PlayVideoButton->Enable(video->IsLoaded());
 	PlayAudioButton->Enable(audio->loaded);
 	// Update grid
-	if (grid->ass != AssFile::top)
-		grid->LoadFromAss(AssFile::top,false,true);
+	grid->UpdateMaps();
 	// Fix style list
 	Styles->Set(grid->ass->GetStyles());
 	// Fix line selection
diff --git a/aegisub/src/frame_main.cpp b/aegisub/src/frame_main.cpp
index 521e459ec..416f2df44 100644
--- a/aegisub/src/frame_main.cpp
+++ b/aegisub/src/frame_main.cpp
@@ -628,10 +628,11 @@ void FrameMain::InitContents() {
 void FrameMain::DeInitContents() {
 	if (detachedVideo) detachedVideo->Destroy();
 	if (stylingAssistant) stylingAssistant->Destroy();
-	AssFile::StackReset();
-	delete AssFile::top;
+	SubsGrid->ClearMaps();
 	delete EditBox;
 	delete videoBox;
+	AssFile::StackReset();
+	delete AssFile::top;
 	HelpButton::ClearPages();
 }
 
@@ -698,17 +699,18 @@ void FrameMain::LoadSubtitles (wxString filename,wxString charset) {
 		}
 
 		// Proceed into loading
-		SubsGrid->Clear();
+		SubsGrid->ClearMaps();
 		AssFile::StackReset();
 		if (isFile) {
 			AssFile::top->Load(filename,charset);
-			SubsGrid->LoadFromAss(AssFile::top,false,true);
+			SubsGrid->SetSelectedSet(SubtitleSelectionController::Selection());
+			SubsGrid->UpdateMaps();
 			wxFileName fn(filename);
 			StandardPaths::SetPathValue(_T("?script"),fn.GetPath());
 			OPT_SET("Path/Last/Subtitles")->SetString(STD_STR(fn.GetPath()));
 		}
 		else {
-			SubsGrid->LoadDefault(AssFile::top);
+			SubsGrid->LoadDefault();
 			StandardPaths::SetPathValue(_T("?script"),_T(""));
 		}
 	}
diff --git a/aegisub/src/frame_main_events.cpp b/aegisub/src/frame_main_events.cpp
index 857845370..f7795cd61 100644
--- a/aegisub/src/frame_main_events.cpp
+++ b/aegisub/src/frame_main_events.cpp
@@ -1051,7 +1051,7 @@ void FrameMain::OnAutomationMacro (wxCommandEvent &event) {
 	int first_sel = SubsGrid->GetFirstSelRow();
 	// Clear all maps from the subs grid before running the macro
 	// The stuff done by the macro might invalidate some of the iterators held by the grid, which will cause great crashing
-	SubsGrid->Clear();
+	SubsGrid->ClearMaps();
 	// Run the macro...
 	activeMacroItems[event.GetId()-Menu_Automation_Macro]->Process(SubsGrid->ass, selected_lines, first_sel, this);
 	// Have the grid update its maps, this properly refreshes it to reflect the changed subs
@@ -1183,7 +1183,7 @@ void FrameMain::OnShiftToFrame (wxCommandEvent &) {
 void FrameMain::OnUndo(wxCommandEvent&) {
 	VideoContext::Get()->Stop();
 	AssFile::StackPop();
-	SubsGrid->LoadFromAss(AssFile::top,true);
+	SubsGrid->UpdateMaps();
 	AssFile::Popping = false;
 }
 
@@ -1191,7 +1191,7 @@ void FrameMain::OnUndo(wxCommandEvent&) {
 void FrameMain::OnRedo(wxCommandEvent&) {
 	VideoContext::Get()->Stop();
 	AssFile::StackRedo();
-	SubsGrid->LoadFromAss(AssFile::top,true);
+	SubsGrid->UpdateMaps();
 	AssFile::Popping = false;
 }
 
diff --git a/aegisub/src/subs_grid.cpp b/aegisub/src/subs_grid.cpp
index bdd6ff90b..60ca2ce40 100644
--- a/aegisub/src/subs_grid.cpp
+++ b/aegisub/src/subs_grid.cpp
@@ -41,6 +41,7 @@
 
 #ifndef AGI_PRE
 #include <algorithm>
+#include <utility>
 
 #include <wx/clipbrd.h>
 #include <wx/filename.h>
@@ -121,6 +122,7 @@ SubtitlesGrid::SubtitlesGrid(FrameMain* parentFr, wxWindow *parent, wxWindowID i
 /// @brief Destructor 
 ///
 SubtitlesGrid::~SubtitlesGrid() {
+	ClearMaps();
 }
 
 
@@ -793,94 +795,44 @@ void SubtitlesGrid::OnAudioClip(wxCommandEvent &event) {
 /// @brief Clears grid and sets it to default 
 /// @param _ass 
 ///
-void SubtitlesGrid::LoadDefault (AssFile *_ass) {
-	if (_ass) {
-		ass = _ass;
-	}
+void SubtitlesGrid::LoadDefault () {
+	ass = AssFile::top;
 	ass->LoadDefault();
-	LoadFromAss(NULL,false,true);
+	UpdateMaps();
 }
 
 
 
-/// @brief Read data from ASS file structure 
-/// @param _ass          
-/// @param keepSelection 
-/// @param dontModify    
-///
-void SubtitlesGrid::LoadFromAss (AssFile *_ass,bool keepSelection,bool dontModify) {
-	// Store selected rows
-	wxArrayInt srows;
-	if (keepSelection) {
-		srows = GetSelection();
-	}
+/// @brief Clear internal data structures
+void SubtitlesGrid::ClearMaps() {
+	line_iter_map.clear();
+	BaseGrid::ClearMaps();
+}
 
-	// Clear grid
+
+
+/// @brief Update internal data structures
+void SubtitlesGrid::UpdateMaps() {
 	BeginBatch();
-	int oldPos = yPos;
-	Clear();
-	if (keepSelection) yPos = oldPos;
 
-	// Clear from video
 	VideoContext::Get()->curLine = NULL;
+	line_iter_map.clear();
+	BaseGrid::ClearMaps();
 
-	// Get subtitles
-	if (_ass) ass = _ass;
-	else {
-		if (!ass) throw _T("Trying to set subs grid to current ass file, but there is none");
-	}
+	ass = AssFile::top;
 
-	// Run through subs adding them
-	int n = 0;
-	AssDialogue *curdiag;
-	ready = false;
-	for (entryIter cur=ass->Line.begin();cur != ass->Line.end();cur++) {
-		curdiag = dynamic_cast<AssDialogue*>(*cur);
-		if (curdiag) {
-			diagMap.push_back(cur);
-			diagPtrMap.push_back(curdiag);
-			selMap.push_back(false);
-			n++;
-		}
-	}
-	ready = true;
+	BaseGrid::UpdateMaps();
 
-	// Restore selection
-	if (keepSelection) {
-		if (srows.empty() || srows[0] >= (signed)selMap.size()) {
-			SelectRow(selMap.size() - 1);
-		}
-		else {
-			for (size_t i=0;i<srows.size();i++) {
-				SelectRow(srows[i],true);
-			}
-		}
+	for (entryIter it = ass->Line.begin(); it != ass->Line.end(); ++it) {
+		AssDialogue *dlg = dynamic_cast<AssDialogue*>(*it);
+		if (dlg) line_iter_map.insert(std::pair<AssDialogue*,entryIter>(dlg, it));
 	}
 
-	// Select first
-	else {
-		SelectRow(0);
-	}
-
-	// Commit
-	if (!AssFile::Popping) {
-		if (dontModify) AssFile::StackPush(_("load"));
-		else ass->FlagAsModified(_("load"));
-	}
-	CommitChanges();
-
 	// Set edit box
 	if (editBox) {
-		int nrows = GetRows();
-		int firstsel = -1;
-		for (int i=0;i<nrows;i++) {
-			if (IsInSelection(i,0)) {
-				firstsel = i;
-				break;
-			}
-		}
+		int firstsel = GetFirstSelRow();
 		editBox->UpdateGlobals();
-		if (_ass) editBox->SetToLine(firstsel);
+		if (ass) editBox->SetToLine(firstsel);
 	}
 
 	// Finish setting layout
@@ -896,20 +848,13 @@ void SubtitlesGrid::LoadFromAss (AssFile *_ass,bool keepSelection,bool dontModif
 /// @return 
 ///
 void SubtitlesGrid::SwapLines(int n1,int n2) {
-	// Check bounds and get iterators
-	int rows = GetRows();
-	if (n1 < 0 || n2 < 0 || n1 >= rows || n2 >= rows) return;
-	entryIter src1 = diagMap.at(n1);
-	entryIter src2 = diagMap.at(n2);
+	AssDialogue *dlg1 = GetDialogue(n1);
+	AssDialogue *dlg2 = GetDialogue(n2);
+	if (n1 == 0 || n2 == 0) return;
 	
-	// Swaps
-	iter_swap(src1,src2);
+	std::swap(*dlg1, *dlg2);
+	UpdateMaps();
 
-	// Update mapping
-	diagMap[n1] = src1;
-	diagPtrMap[n1] = (AssDialogue*) *src1;
-	diagMap[n2] = src2;
-	diagPtrMap[n2] = (AssDialogue*) *src2;
 	ass->FlagAsModified(_("swap lines"));
 	CommitChanges();
 }
@@ -923,20 +868,11 @@ void SubtitlesGrid::SwapLines(int n1,int n2) {
 /// @param update 
 ///
 void SubtitlesGrid::InsertLine(AssDialogue *line,int n,bool after,bool update) {
-	// Check bounds and get iterators
-	entryIter pos = diagMap.at(n);
+	AssDialogue *rel_line = GetDialogue(n) + (after?1:0);
+	entryIter pos = line_iter_map[rel_line];
 	
-	// Insert
-	if (after) {
-		n++;
-		pos++;
-	}
 	entryIter newIter = ass->Line.insert(pos,line);
-	//InsertRows(n);
-	//SetRowToLine(n,line);
-	diagMap.insert(diagMap.begin() + n,newIter);
-	diagPtrMap.insert(diagPtrMap.begin() + n,(AssDialogue*)(*newIter));
-	selMap.insert(selMap.begin() + n,false);
+	UpdateMaps();
 
 	// Update
 	if (update) {
@@ -1100,19 +1036,20 @@ void SubtitlesGrid::PasteLines(int n,bool pasteOver) {
 void SubtitlesGrid::DeleteLines(wxArrayInt target, bool flagModified) {
 	// Check if it's wiping file
 	int deleted = 0;
+	entryIter before_first = line_iter_map[GetDialogue(0)]; --before_first;
 
 	// Delete lines
 	int size = target.Count();
 	for (int i=0;i<size;i++) {
-		delete (*diagMap.at(target[i]));
-		ass->Line.erase(diagMap.at(target[i]));
+		ass->Line.erase(line_iter_map[GetDialogue(target[i])]);
 		deleted++;
 	}
 
 	// Add default line if file was wiped
 	if (GetRows() == deleted) {
 		AssDialogue *def = new AssDialogue;
-		ass->Line.push_back(def);
+		++before_first;
+		ass->Line.insert(before_first, def);
 	}
 
 	// Update
@@ -1124,7 +1061,7 @@ void SubtitlesGrid::DeleteLines(wxArrayInt target, bool flagModified) {
 	}
 
 	// Update selected line
-	int newSelected = MID(0, editBox->linen,GetRows() - 1);
+	int newSelected = ClampSignedInteger32(editBox->linen, 0, GetRows()-1);
 	editBox->SetToLine(newSelected);
 	SelectRow(newSelected);
 }
@@ -1526,25 +1463,20 @@ void SubtitlesGrid::SetVideoToSubs(bool start) {
 
 
 
-/// @brief (ie. not as displayed in the grid but as represented in the file) Retrieve a list of selected lines in the actual ASS file 
+/// @brief Retrieve a list of selected lines in the actual ASS file (ie. not as displayed in the grid but as represented in the file)
 /// @return 
 ///
 std::vector<int> SubtitlesGrid::GetAbsoluteSelection() {
 	std::vector<int> result;
 	result.reserve(GetNumberSelection());
 
-	int nrows = GetRows();
-	for (int i = 0; i != nrows; ++i) {
-		if (selMap.at(i)) {
-			entryIter l = diagMap.at(i);
-			int n = 0;
-			for (std::list<AssEntry*>::iterator j = ass->Line.begin(); j != ass->Line.end(); ++j, ++n) {
-				if (j == l) {
-					result.push_back(n);
-					break;
-				}
-			}
-		}
+	Selection sel;
+	GetSelectedSet(sel);
+
+	int line_index = 0;
+	for (entryIter it = ass->Line.begin(); it != ass->Line.end(); ++it, ++line_index) {
+		if (sel.find(dynamic_cast<AssDialogue*>(*it)) != sel.end())
+			result.push_back(line_index);
 	}
 
 	return result;
@@ -1552,21 +1484,25 @@ std::vector<int> SubtitlesGrid::GetAbsoluteSelection() {
 
 
 
-/// @brief selection vector must be sorted Update list of selected lines from absolute selection 
+/// @brief Update list of selected lines from absolute selection
 /// @param selection 
 ///
 void SubtitlesGrid::SetSelectionFromAbsolute(std::vector<int> &selection) {
+	Selection newsel;
 
-	int nrows = GetRows();
+	std::sort(selection.begin(), selection.end());
+
+	int i = 0;
 	std::list<AssEntry*>::iterator j = ass->Line.begin();
-	int index = 0;
-	for (int i = 0; i != nrows; ++i) {
-		entryIter l = diagMap.at(i);
-		while(j != l && j != ass->Line.end()) ++j, ++index;
-		if(j == l && binary_search(selection.begin(), selection.end(), index)) {
-			selMap[i] = true;
-		} else selMap[i] = false;
+	
+	for (size_t selveci = 0; selveci < selection.size(); ++selveci) {
+		while (i != selection[selveci] && j != ass->Line.end()) ++i, ++j;
+		if (j == ass->Line.end()) break; /// @todo Report error somehow
+		AssDialogue *dlg = dynamic_cast<AssDialogue*>(*j);
+		if (dlg) newsel.insert(dlg);
 	}
+
+	SetSelectedSet(newsel);
 }
 
 
diff --git a/aegisub/src/subs_grid.h b/aegisub/src/subs_grid.h
index 4dd129050..5c8b27c41 100644
--- a/aegisub/src/subs_grid.h
+++ b/aegisub/src/subs_grid.h
@@ -78,10 +78,6 @@ typedef std::list<AssEntry*>::iterator entryIter;
 /// DOCME
 class SubtitlesGrid: public BaseGrid {
 private:
-
-	/// DOCME
-	bool ready;
-
 	void OnPopupMenu(bool alternate=false);
 	void OnKeyDown(wxKeyEvent &event);
 
@@ -110,6 +106,8 @@ private:
 	void OnAudioClip(wxCommandEvent &event);
 	void OnShowColMenu(wxCommandEvent &event);
 
+	std::map<AssDialogue*,entryIter> line_iter_map;
+
 public:
 
 	/// DOCME
@@ -118,10 +116,12 @@ public:
 	SubtitlesGrid(FrameMain* parentFrame,wxWindow *parent, wxWindowID id, const wxPoint& pos = wxDefaultPosition, const wxSize& size = wxDefaultSize, long style = wxWANTS_CHARS, const wxString& name = wxPanelNameStr);
 	~SubtitlesGrid();
 
-	void LoadDefault(AssFile *ass=NULL);
-	void LoadFromAss(AssFile *ass=NULL,bool keepSelection=false,bool dontModify=false);
+	void LoadDefault();
 	void CommitChanges(bool force=false,bool videoOnly=false);
 
+	void ClearMaps();
+	void UpdateMaps();
+
 	void SetVideoToSubs(bool start);
 	void SetSubsToVideo(bool start);