This commit adds some missing features to markers in action editor,

and also fixes some further segfaults.

Now it is possible to 'surf' (jump) to different markers. This is only
possible through the hotkeys for this:
* Page Up - Next Marker
* Page Down - Previous Marker

These hotkeys match the ones in the timeline. In order to do so,
I've had to reassign two (rarely used/obscure) hotkeys:
* 'Ctrl Page Up' is now move selected action channel up (was Page Up)
* 'Ctrl Page Down' is no move selected action channel down (was Page Down)
I should also mention here that
* 'Shift Page Up' is move action channel to top
* 'Shift Page Down' is move action channel to bottom

3 files changed, 121 insertions, 45 deletions

diff --git a/source/blender/include/BIF_editaction.h b/source/blender/include/BIF_editaction.h
index ce744b2b3b3..459884df704 100644
--- a/source/blender/include/BIF_editaction.h
+++ b/source/blender/include/BIF_editaction.h
@@ -85,15 +85,17 @@ void clean_actionchannels(struct bAction *act);
 /* Marker Operations */
 struct ListBase *get_saction_markers(struct SpaceAction *saction);
 struct TimeMarker *find_nearest_saction_marker(struct ListBase *markers);
+void get_minmax_saction_markers(struct ListBase *markers, float *first, float *last);
 void add_saction_marker(struct ListBase *markers, int frame);
 void duplicate_saction_markers(struct ListBase *markers);
 void remove_saction_markers(struct ListBase *markers);
 void rename_saction_markers(struct ListBase *markers);
 void transform_saction_markers(int mode, int smode);
-void deselect_saction_markers(struct ListBase *markers, int test, int sel);
+void deselect_saction_markers(struct ListBase *markers, short test, short sel);
 void borderselect_saction_markers(struct ListBase *markers, float xmin, float xmax, int selectmode);
-void selectkeyscolumns_saction_markers(struct ListBase *markers);
-void selectkeysbetween_saction_markers(struct ListBase *markers);
+void nextprev_saction_markers(ListBase *markers, short dir);
+void selectkeys_columns_markers(struct ListBase *markers);
+void selectkeys_between_markers(struct ListBase *markers);
 
 /* channel/strip operations */
 void up_sel_action(void);
diff --git a/source/blender/src/editaction.c b/source/blender/src/editaction.c
index 921478971e0..80bb0483eba 100644
--- a/source/blender/src/editaction.c
+++ b/source/blender/src/editaction.c
@@ -2636,23 +2636,25 @@ void winqreadactionspace(ScrArea *sa, void *spacedata, BWinEvent *evt)
 			
 		case MKEY:
 			/* marker operations */
-			if (G.qual == 0)
-				add_saction_marker(markers, CFRA);
-			else if (G.qual == LR_ALTKEY) {
-				if( okee("Erase selected markers")==0 ) 
+			if (markers != NULL) {
+				if (G.qual == 0)
+					add_saction_marker(markers, CFRA);
+				else if (G.qual == LR_ALTKEY) {
+					if( okee("Erase selected markers")==0 ) 
+						break;
+					remove_saction_markers(markers);
+				}
+				else if (G.qual == LR_CTRLKEY)
+					rename_saction_markers(markers);
+				else if (G.qual == LR_SHIFTKEY)
+					transform_saction_markers('g', 0);
+				else if (G.qual == (LR_CTRLKEY|LR_SHIFTKEY))
+					duplicate_saction_markers(markers);
+				else 
 					break;
-				remove_saction_markers(markers);
-			}
-			else if (G.qual == LR_CTRLKEY)
-				rename_saction_markers(markers);
-			else if (G.qual == LR_SHIFTKEY)
-				transform_saction_markers('g', 0);
-			else if (G.qual == (LR_CTRLKEY|LR_SHIFTKEY))
-				duplicate_saction_markers(markers);
-			else 
-				break;
-			allqueue(REDRAWACTION, 0);
-			allqueue(REDRAWTIME, 0);
+				allqueue(REDRAWACTION, 0);
+				allqueue(REDRAWTIME, 0);
+			}
 			break;
 			
 		case NKEY:
@@ -2710,30 +2712,30 @@ void winqreadactionspace(ScrArea *sa, void *spacedata, BWinEvent *evt)
 
 		case PAGEUPKEY:
 			if (key) {
-				/* to do */
+				/* only jump to markers possible (key channels can't be moved yet) */
+				nextprev_saction_markers(markers, 1);
 			}
 			else {
-				if(G.qual & LR_SHIFTKEY) {
+				if(G.qual & LR_SHIFTKEY)
 					top_sel_action();
-				}
-				else
-				{
+				else if (G.qual & LR_CTRLKEY)
 					up_sel_action();
-				}
-				
+				else
+					nextprev_saction_markers(markers, 1);
 			}
 			break;
 		case PAGEDOWNKEY:
 			if (key) {
-				/* to do */
+				/* only jump to markers possible (key channels can't be moved yet) */
+				nextprev_saction_markers(markers, -1);
 			}
 			else {
-				if(G.qual & LR_SHIFTKEY) {
+				if(G.qual & LR_SHIFTKEY)
 					bottom_sel_action();
-				}
+				else if (G.qual & LR_CTRLKEY) 
+					down_sel_action();
 				else
-				down_sel_action();
-				
+					nextprev_saction_markers(markers, -1);
 			}
 			break;
 		case DELKEY:
@@ -2955,6 +2957,9 @@ void remove_saction_markers(ListBase *markers)
 {
 	TimeMarker *marker;
 	
+	if (markers == NULL)
+		return;
+	
 	for(marker= markers->first; marker; marker= marker->next) {
 		if(marker->flag & SELECT){
 			BLI_freelinkN(markers, marker);
@@ -2970,6 +2975,9 @@ void rename_saction_markers(ListBase *markers)
 	TimeMarker *marker;
 	char name[64];
 	
+	if (markers == NULL)
+		return;
+	
 	for(marker= markers->first; marker; marker= marker->next) {
 		if(marker->flag & SELECT) {
 			sprintf(name, marker->name);
@@ -3131,11 +3139,51 @@ TimeMarker *find_nearest_saction_marker(ListBase *markers)
 	return NULL;
 }
 
+/* select next/previous marker */
+void nextprev_saction_markers(ListBase *markers, short dir)
+{
+	TimeMarker *marker, *cur=NULL, *first, *last;
+	int mindist= MAXFRAME, dist;
+	
+	if (markers == NULL)
+		return;
+	
+	first= last= markers->first; 
+	for(marker= markers->first; marker; marker= marker->next) {
+		/* find closest to current frame first */
+		dist= (marker->frame/G.scene->r.framelen) - CFRA;
+		if(dir==1 && dist>0 && dist<mindist) {
+			mindist= dist;
+			cur= marker;
+		}
+		else if(dir==-1 && dist<0 && -dist<mindist) {
+			mindist= -dist;
+			cur= marker;
+		}
+		/* find first/last */
+		if(marker->frame > last->frame) last= marker;
+		if(marker->frame < first->frame) first= marker;
+	}
+	
+	if(cur==NULL) {
+		if(dir==1) cur= first;
+		else cur= last;
+	}
+	if(cur) {
+		CFRA= cur->frame/G.scene->r.framelen;
+		update_for_newframe();
+		allqueue(REDRAWALL, 0);
+	}
+}
+
 /* select/deselect all TimeMarkers */
-void deselect_saction_markers(ListBase *markers, int test, int sel)
+void deselect_saction_markers(ListBase *markers, short test, short sel)
 {
 	TimeMarker *marker;
 	
+	if (markers == NULL)
+		return;
+	
 	/* check if need to find out whether to how to select markers */
 	if (test) {
 		/* dependant on existing selection */
@@ -3179,6 +3227,9 @@ void borderselect_saction_markers(ListBase *markers, float xmin, float xmax, int
 {
 	TimeMarker *marker;
 	
+	if (markers == NULL)
+		return;
+	
 	for(marker= markers->first; marker; marker= marker->next) {
 		if ((marker->frame > xmin) && (marker->frame <= xmax)) {
 			switch (selectmode) {
@@ -3195,6 +3246,28 @@ void borderselect_saction_markers(ListBase *markers, float xmin, float xmax, int
 	}
 }
 
+void get_minmax_saction_markers(ListBase *markers, float *first, float *last)
+{
+	TimeMarker *marker;
+	float min, max;
+	
+	if (!markers)
+		return;
+		
+	min= ((TimeMarker *)markers->first)->frame;
+	max= ((TimeMarker *)markers->last)->frame;
+	
+	for (marker= markers->first; marker; marker= marker->next) {
+		if (marker->frame < min)
+			min= marker->frame;
+		else if (marker->frame > max)
+			max= marker->frame;
+	}
+	
+	*first= min;
+	*last= max;
+}
+
 /* ************************************* Action Channel Ordering *********************************** */
 
 void top_sel_action()
diff --git a/source/blender/src/header_action.c b/source/blender/src/header_action.c
index eecfcda1359..27893184c24 100644
--- a/source/blender/src/header_action.c
+++ b/source/blender/src/header_action.c
@@ -439,8 +439,8 @@ static uiBlock *action_selectmenu(void *arg_unused)
 					 "Select Keys Column|K", 0, yco-=20, 
 					 menuwidth, 19, NULL, 0.0, 0.0, 0, 
 					 ACTMENU_SEL_COLUMN, "");
-					
-	/*
+	
+/*	
 	uiDefIconTextBut(block, BUTM, 1, ICON_BLANK1, 
 					 "Select Keys At Markers|CTRL K", 0, yco-=20, 
 					 menuwidth, 19, NULL, 0.0, 0.0, 0, 
@@ -450,7 +450,7 @@ static uiBlock *action_selectmenu(void *arg_unused)
 					 "Select Keys Between Markers|SHIFT K", 0, yco-=20, 
 					 menuwidth, 19, NULL, 0.0, 0.0, 0, 
 					 ACTMENU_SEL_MARKERS_KEYSBETWEEN, "");
-	*/
+*/
 	
 	if(curarea->headertype==HEADERTOP) {
 		uiBlockSetDirection(block, UI_DOWN);
@@ -774,11 +774,11 @@ static uiBlock *action_keymenu_chanposmenu(void *arg_unused)
 	uiBlockSetButmFunc(block, do_action_keymenu_chanposmenu, NULL);
 
 	uiDefIconTextBut(block, BUTM, 1, ICON_BLANK1, 
-					 "Move Up|Page Up", 0, yco-=20, 
+					 "Move Up|Ctrl Page Up", 0, yco-=20, 
 					 menuwidth, 19, NULL, 0.0, 0.0, 0, 
 					 ACTMENU_KEY_CHANPOS_MOVE_CHANNEL_UP, "");
 	uiDefIconTextBut(block, BUTM, 1, ICON_BLANK1, 
-					 "Move Down|Page Down", 0, yco-=20, 
+					 "Move Down|Ctrl Page Down", 0, yco-=20, 
 					 menuwidth, 19, NULL, 0.0, 0.0, 0, 
 					 ACTMENU_KEY_CHANPOS_MOVE_CHANNEL_DOWN, "");
 	
@@ -927,30 +927,30 @@ static uiBlock *action_keymenu(void *arg_unused)
 static void do_action_markermenu(void *arg, int event)
 {	
 	SpaceAction *saction;
-	ListBase *lb = NULL;
+	ListBase *markers = NULL;
 	
 	saction= curarea->spacedata.first;
 	if (!saction)
 		return;
 
 	/* get set of markers */
-	lb= get_saction_markers(saction);
-	if (lb == NULL) 
+	markers= get_saction_markers(saction);
+	if (markers == NULL) 
 		return;
 	
 	switch(event)
 	{
 		case ACTMENU_MARKERS_ADD:
-			add_saction_marker(lb, CFRA);
+			add_saction_marker(markers, CFRA);
 			break;
 		case ACTMENU_MARKERS_DUPLICATE:
-			duplicate_saction_markers(lb);
+			duplicate_saction_markers(markers);
 			break;
 		case ACTMENU_MARKERS_DELETE:
-			remove_saction_markers(lb);
+			remove_saction_markers(markers);
 			break;
 		case ACTMENU_MARKERS_NAME:
-			rename_saction_markers(lb);
+			rename_saction_markers(markers);
 			break;
 		case ACTMENU_MARKERS_MOVE:
 			transform_saction_markers('g', 0);
@@ -1075,7 +1075,8 @@ void action_buttons(void)
 					  "Key", xco, -2, xmax-3, 24, "");
 		xco+= xmax;
 		
-		if (G.saction->markert != SACTION_NOMARKERS) {
+		if ((G.saction->markert != SACTION_NOMARKERS) &&
+			(G.saction->action != NULL)) {
 			xmax= GetButStringLength("Marker");
 			uiDefPulldownBut(block, action_markermenu, NULL, 
 						  "Marker", xco, -2, xmax-3, 24, "");