pin selection of closest entity in map editor

Pressing the middle mouse button toggles a pin on the "closest entity"
selector. The HUD will indicate the lock by showing "pinned" instead of
"closest" entity. All actions, that would otherwise affect the closest
entity, will affect the pinned entity instead. Deleting the locked entity
will unlock it.

toggleclosestentpin
  Toggles the pin on the "closest ent" selector. Bound to MOUSE3
  by default.

DOCREF togglelockclosestent

config/resetbinds.cfg

@@ -27,6 +27,7 @@ bind MOUSE1 attack
 bind MOUSE2 altaction
 editbind MOUSE2 [ showmenu editing ]
 bind MOUSE3 weapon
+editbind MOUSE3 toggleclosestentpin
 bind MOUSE4 key_universaldelta_plus
 bind MOUSE5 key_universaldelta_minus
 bind BACKSPACE dropflag

source/src/clientgame.cpp

@@ -1085,6 +1085,7 @@ void resetmap(bool mrproper)
     pruneundos();
     changedents.setsize(0);
     deleted_ents.setsize(0);
+    pinnedclosestent = false;
     particlereset();
     if(mrproper)
     {

source/src/editing.cpp

@@ -106,7 +106,7 @@ char *editinfo()
     {
         entity &c = ents[e];
         int t = c.type < MAXENTTYPES ? c.type : 0;
-        formatstring(info)("closest entity: %s (%s)", entnames[t], formatentityattributes(c, true));
+        formatstring(info)("%s entity: %s (%s)", pinnedclosestent ? "\fs\f3pinned\fr" : "closest", entnames[t], formatentityattributes(c, true));
         const char *slotinfo = "unassigned slot";
         if(t == MAPMODEL)
         {

source/src/protos.h

@@ -485,6 +485,7 @@ extern void calcmapdims();
 extern bool empty_world(int factor, bool force);
 extern void remip(const block &b, int level = 0);
 extern void remipmore(const block &b, int level = 0);
+extern bool pinnedclosestent;
 extern int closestent();
 extern void deletesoundentity(entity &e);
 extern int findtype(const char *what);

source/src/world.cpp

@@ -128,9 +128,18 @@ void closestenttype(char *what)
 COMMAND(nextclosestent, "");
 COMMAND(closestenttype, "s");
 
+bool pinnedclosestent = false;
+static int pinnedent = -1;
+COMMANDF(toggleclosestentpin, "", () { pinnedclosestent = ents.inrange((pinnedent = pinnedclosestent ? -1 : closestent())); });
+
 int closestent()        // used for delent and edit mode ent display
 {
     if(noteditmode("closestent")) return -1;
+    if(pinnedclosestent)
+    {
+        if(ents.inrange(pinnedent) && ents[pinnedent].type != NOTUSED) return pinnedent;
+        pinnedclosestent = false; // release lock when ent is deleted
+    }
     int best = -1, bcnt = 0;
     float bdist = 99999;
     loopj(3)