For long on the wanna-have list;

Ipocurves with "Auto" handles now have option to remain horizontal on the
extrema (tops & valleys). Use ALT+H to set this per selected curve.
Note this is a per-curve feature, not per-handle.

If it works satisfying I can check on making this the default new added
curve.

source/blender/blenkernel/intern/action.c

@@ -166,6 +166,7 @@ bAction* copy_action(bAction *src)
 
 /* ************************ Pose channels *************** */
 
+/* usually used within a loop, so we got a N^2 slowdown */
 bPoseChannel *get_pose_channel(const bPose *pose, const char *name)
 {
 	bPoseChannel *chan;
@@ -173,6 +174,7 @@ bPoseChannel *get_pose_channel(const bPose *pose, const char *name)
 	if(pose==NULL) return NULL;
 	
 	for (chan=pose->chanbase.first; chan; chan=chan->next) {
+		if(chan->name[0] == name[0])
 			if (!strcmp (chan->name, name))
 				return chan;
 	}

source/blender/blenkernel/intern/curve.c

@@ -1936,7 +1936,7 @@ void makeBevelList(Object *ob)
  *		1: nothing,  1:auto,  2:vector,  3:aligned
  */
 
-
+/* mode: is not zero when IpoCurve, is 2 when forced horizontal for autohandles */
 void calchandleNurb(BezTriple *bezt, BezTriple *prev, BezTriple *next, int mode)
 {
 	float *p1,*p2,*p3,pt[3];
@@ -2006,16 +2006,33 @@ void calchandleNurb(BezTriple *bezt,BezTriple *prev, BezTriple *next, int mode)
 				*(p2-3)= *p2-vx*len1;
 				*(p2-2)= *(p2+1)-vy*len1;
 				*(p2-1)= *(p2+2)-vz*len1;
+				
+				if(mode==2 && next && prev) {	// keep horizontal if extrema
+					float ydiff1= prev->vec[1][1] - bezt->vec[1][1];
+					float ydiff2= next->vec[1][1] - bezt->vec[1][1];
+					if( (ydiff1<0.0 && ydiff2<0.0) || (ydiff1>0.0 && ydiff2>0.0) ) {
+						bezt->vec[0][1]= bezt->vec[1][1];
+					}
+				}
 			}
 			if(bezt->h2==HD_AUTO) {
 				len2/=len;
 				*(p2+3)= *p2+vx*len2;
 				*(p2+4)= *(p2+1)+vy*len2;
 				*(p2+5)= *(p2+2)+vz*len2;
+				
+				if(mode==2 && next && prev) {	// keep horizontal if extrema
+					float ydiff1= prev->vec[1][1] - bezt->vec[1][1];
+					float ydiff2= next->vec[1][1] - bezt->vec[1][1];
+					if( (ydiff1<0.0 && ydiff2<0.0) || (ydiff1>0.0 && ydiff2>0.0) ) {
+						bezt->vec[2][1]= bezt->vec[1][1];
 					}
 				}
 			}
 			
+		}
+	}
+
 	if(bezt->h1==HD_VECT) {	/* vector */
 		dx/=3.0; 
 		dy/=3.0; 
@@ -2037,6 +2054,7 @@ void calchandleNurb(BezTriple *bezt,BezTriple *prev, BezTriple *next, int mode)
 	len1= VecLenf(p2, p2-3);
 	if(len1==0.0) len1=1.0;
 	if(len2==0.0) len2=1.0;
+
 	if(bezt->f1 & 1) { /* order of calculation */
 		if(bezt->h2==HD_ALIGN) {	/* aligned */
 			len= len2/len1;
@@ -2224,7 +2242,8 @@ void sethandlesNurb(short code)
 {
 	/* code==1: set autohandle */
 	/* code==2: set vectorhandle */
-	/* if code==3 (HD_ALIGN) it toggle, vectorhandles become HD_FREE */
+	/* code==3 (HD_ALIGN) it toggle, vectorhandles become HD_FREE */
+	/* code==4: sets icu flag to become IPO_AUTO_HORIZ, horizontal extremes on auto-handles */
 	Nurb *nu;
 	BezTriple *bezt;
 	short a, ok=0;

source/blender/blenkernel/intern/ipo.c

@@ -404,6 +404,9 @@ void calchandles_ipocurve(IpoCurve *icu)
 		if(bezt->vec[0][0]>bezt->vec[1][0]) bezt->vec[0][0]= bezt->vec[1][0];
 		if(bezt->vec[2][0]<bezt->vec[1][0]) bezt->vec[2][0]= bezt->vec[1][0];
 
+		if(icu->flag & IPO_AUTO_HORIZ) 
+			calchandleNurb(bezt, prev, next, 2);	/* 2==special autohandle && keep extrema horizontal */
+		else
 			calchandleNurb(bezt, prev, next, 1);	/* 1==special autohandle */
 	
 		prev= bezt;

source/blender/makesdna/DNA_ipo_types.h

@@ -320,10 +320,10 @@ typedef short IPO_Channel;
 #define CO_ROLL		9
 */
 
-/* these are ipo-specific */
+/* these are IpoCurve specific */
 /* **************** IPO ********************* */
 
-/* vartype */
+/* icu->vartype */
 #define IPO_CHAR		0
 #define IPO_SHORT		1
 #define IPO_INT			2
@@ -335,29 +335,30 @@ typedef short IPO_Channel;
 #define IPO_BEZTRIPLE	100
 #define IPO_BPOINT		101
 
-
+/* icu->vartype */
 #define IPO_BITS		16
 #define IPO_CHAR_BIT	16
 #define IPO_SHORT_BIT	17
 #define IPO_INT_BIT		18
 
-/* ipo */
+/* icu->ipo */
 #define IPO_CONST		0
 #define IPO_LIN			1
 #define IPO_BEZ			2
 #define IPO_MIXED		3
 
-/* extrap */
+/* icu->extrap */
 #define IPO_HORIZ		0
 #define IPO_DIR			1
 #define IPO_CYCL		2
 #define IPO_CYCLX		3
 
-/* flag */
+/* icu->flag */
 #define IPO_VISIBLE		1
 #define IPO_SELECT		2
 #define IPO_EDIT		4
 #define IPO_LOCK		8
+#define IPO_AUTO_HORIZ	16
 
 #endif
 

source/blender/src/editipo.c

@@ -2926,6 +2926,27 @@ void sethandles_ipo_keys(Ipo *ipo, int code)
 
 }
 
+static void ipo_curves_auto_horiz(void)
+{
+    EditIpo *ei;
+	int a, set= 1;
+	
+	ei= G.sipo->editipo;
+	for(a=0; a<G.sipo->totipo; a++, ei++) {
+		if ISPOIN3(ei, flag & IPO_VISIBLE, flag & IPO_SELECT, icu)
+			if(ei->flag & IPO_AUTO_HORIZ) set= 0;
+	}
+	
+	ei= G.sipo->editipo;
+	for(a=0; a<G.sipo->totipo; a++, ei++) {
+		if ISPOIN3(ei, flag & IPO_VISIBLE, flag & IPO_SELECT, icu) {
+			if(set) ei->flag |= IPO_AUTO_HORIZ;
+			else ei->flag &= ~IPO_AUTO_HORIZ;
+		}
+	}
+	update_editipo_flags();
+}
+
 void sethandles_ipo(int code)
 {
 	/* this function lets you set bezier handles all to
@@ -2950,6 +2971,11 @@ void sethandles_ipo(int code)
 		selected_bezier_loop(vis_edit_icu_bez, set_bezier_vector,
                          calchandles_ipocurve);
 		break;
+	case 4:
+		/* set to enforce autohandles to be horizontal on extremes */
+		ipo_curves_auto_horiz();
+		
+		break;
 	default:
 		if (selected_bezier_loop(vis_edit_icu_bez, bezier_isfree, NULL) ) {
 			/*** Set to free ***/
@@ -3156,7 +3182,7 @@ void del_ipo()
 	
 	if( okee("Erase selected")==0 ) return;
 
-	// eerste doorloop, kunnen hele stukken weg? 
+	// first round, can we delete entire parts? 
 	ei= G.sipo->editipo;
 	for(a=0; a<G.sipo->totipo; a++, ei++) {
 	
@@ -3197,7 +3223,7 @@ void del_ipo()
 		}
 	}
 	
-	// tweede doorloop, kleine stukken weg: alleen curves 
+	// 2nd round, small parts: just curves 
 	ei= G.sipo->editipo;
 	for(b=0; b<G.sipo->totipo; b++, ei++) {
 		if ISPOIN(ei, flag & IPO_VISIBLE, icu) {

source/blender/src/space.c

@@ -2015,9 +2015,11 @@ static void winqreadipospace(ScrArea *sa, void *spacedata, BWinEvent *evt)
 				transform_ipo('g');
 			break;
 		case HKEY:
-			if((G.qual==LR_SHIFTKEY))
+			if(G.qual==LR_ALTKEY)
+				sethandles_ipo(4);		// tsk tsk ton!
+			if(G.qual==LR_SHIFTKEY)
 				sethandles_ipo(HD_AUTO);
-			else if((G.qual==0))
+			else if(G.qual==0)
 				sethandles_ipo(HD_ALIGN);
 			break;
 		case JKEY: