diff --git a/dat/themerms.lua b/dat/themerms.lua
index 4b2aeb05d..1c97015f2 100644
--- a/dat/themerms.lua
+++ b/dat/themerms.lua
@@ -17,6 +17,139 @@
 -- core calls themerooms_generate() multiple times per level
 -- to generate a single themed room.
 
+themeroom_fills = {
+
+   -- Ice room
+   function(rm)
+      local ice = selection.room();
+      des.terrain(ice, "I");
+      if (percent(25)) then
+         local mintime = 1000 - (nh.level_difficulty() * 100);
+         local ice_melter = function(x,y)
+            nh.start_timer_at(x,y, "melt-ice", mintime + nh.rn2(1000));
+         end;
+         ice:iterate(ice_melter);
+      end
+   end,
+
+   -- Boulder room
+   {
+      mindiff = 4,
+      contents = function(rm)
+         local locs = selection.room():percentage(30);
+         local func = function(x,y)
+            if (percent(50)) then
+               des.object("boulder", x, y);
+            else
+               des.trap("rolling boulder", x, y);
+            end
+         end;
+         locs:iterate(func);
+      end
+   },
+
+   -- Spider nest
+   function(rm)
+      local spooders = nh.level_difficulty() > 8;
+      local locs = selection.room():percentage(30);
+      local func = function(x,y)
+         des.trap({ type = "web", x = x, y = y,
+                    spider_on_web = spooders and percent(80) });
+      end
+      locs:iterate(func);
+   end,
+
+   -- Trap room
+   function(rm)
+      local traps = { "arrow", "dart", "falling rock", "bear",
+                      "land mine", "sleep gas", "rust",
+                      "anti magic" };
+      shuffle(traps);
+      local locs = selection.room():percentage(30);
+      local func = function(x,y)
+         des.trap(traps[1], x, y);
+      end
+      locs:iterate(func);
+   end,
+
+   -- Buried treasure
+   function(rm)
+      des.object({ id = "chest", buried = true, contents = function()
+                      for i = 1, d(3,4) do
+                         des.object();
+                      end
+      end });
+   end,
+
+   -- Massacre
+   function(rm)
+      local mon = { "apprentice", "warrior", "ninja", "thug",
+                    "hunter", "acolyte", "abbot", "page",
+                    "attendant", "neanderthal", "chieftain",
+                    "student", "wizard", "valkyrie", "tourist",
+                    "samurai", "rogue", "ranger", "priestess",
+                    "priest", "monk", "knight", "healer",
+                    "cavewoman", "caveman", "barbarian",
+                    "archeologist" };
+      local idx = math.random(#mon);
+      for i = 1, d(5,5) do
+         if (percent(10)) then idx = math.random(#mon); end
+         des.object({ id = "corpse", montype = mon[idx] });
+      end
+   end,
+
+   -- Statuary
+   function(rm)
+      for i = 1, d(5,5) do
+         des.object({ id = "statue" });
+      end
+      for i = 1, d(3) do
+         des.trap("statue");
+      end
+   end,
+
+   -- Light source
+   {
+      eligible = function(rm) return rm.lit == false; end,
+      contents = function(rm)
+         des.object({ id = "oil lamp", lit = true });
+      end
+   },
+
+   -- Temple of the gods
+   function(rm)
+      des.altar({ align = align[1] });
+      des.altar({ align = align[2] });
+      des.altar({ align = align[3] });
+   end,
+
+   -- Ghost of an Adventurer
+   function(rm)
+      local loc = selection.room():rndcoord(0);
+      des.monster({ id = "ghost", asleep = true, waiting = true, coord = loc });
+      if percent(65) then
+         des.object({ id = "dagger", coord = loc, buc = "not-blessed" });
+      end
+      if percent(55) then
+         des.object({ class = ")", coord = loc, buc = "not-blessed" });
+      end
+      if percent(45) then
+         des.object({ id = "bow", coord = loc, buc = "not-blessed" });
+         des.object({ id = "arrow", coord = loc, buc = "not-blessed" });
+      end
+      if percent(65) then
+         des.object({ class = "[", coord = loc, buc = "not-blessed" });
+      end
+      if percent(20) then
+         des.object({ class = "=", coord = loc, buc = "not-blessed" });
+      end
+      if percent(20) then
+         des.object({ class = "?", coord = loc, buc = "not-blessed" });
+      end
+   end,
+
+};
+
 themerooms = {
    {
      -- the "default" room
@@ -71,114 +204,26 @@ themerooms = {
       });
    end,
 
-   -- Ice room
-   function()
-      des.room({ type = "themed", filled = 1,
-                 contents = function()
-                    local ice = selection.floodfill(1,1);
-                    des.terrain(ice, "I");
-                    if (percent(25)) then
-                       local mintime = 1000 - (nh.level_difficulty() * 100);
-                       local ice_melter = function(x,y)
-                          nh.start_timer_at(x,y, "melt-ice", mintime + nh.rn2(1000));
-                       end;
-                       ice:iterate(ice_melter);
-                    end
-                 end
-      });
-   end,
-
-   -- Boulder room
    {
-      mindiff = 4,
+      frequency = 6,
       contents = function()
-         des.room({ type = "themed",
-                  contents = function(rm)
-                     for x = 0, rm.width - 1 do
-                        for y = 0, rm.height - 1 do
-                           if (percent(30)) then
-                              if (percent(50)) then
-                                 des.object("boulder");
-                              else
-                                 des.trap("rolling boulder");
-                              end
-                           end
-                        end
-                     end
-                  end
-         });
+         des.room({ type = "themed", contents = themeroom_fill });
       end
    },
 
-   -- Spider nest
-   function()
-      des.room({ type = "themed",
-                  contents = function(rm)
-                     local spooders = nh.level_difficulty() > 8;
-                     for x = 0, rm.width - 1 do
-                        for y = 0, rm.height - 1 do
-                           if (percent(30)) then
-                              des.trap({ type = "web", x = x, y = y,
-                                   spider_on_web = spooders and percent(80) });
-                           end
-                        end
-                     end
-                  end
-      });
-   end,
+   {
+      frequency = 2,
+      contents = function()
+         des.room({ type = "themed", lit = 0, contents = themeroom_fill });
+      end
+   },
 
-   -- Trap room
-   function()
-      des.room({ type = "themed", filled = 0,
-                 contents = function(rm)
-                    local traps = { "arrow", "dart", "falling rock", "bear",
-                                    "land mine", "sleep gas", "rust",
-                                    "anti magic" };
-                    shuffle(traps);
-                    for x = 0, rm.width - 1 do
-                       for y = 0, rm.height - 1 do
-                          if (percent(30)) then
-                             des.trap(traps[1], x, y);
-                          end
-                       end
-                    end
-                 end
-      });
-   end,
-
-   -- Buried treasure
-   function()
-      des.room({ type = "ordinary", filled = 1,
-                 contents = function()
-                    des.object({ id = "chest", buried = true, contents = function()
-                                    for i = 1, d(3,4) do
-                                       des.object();
-                                    end
-                    end });
-                 end
-      });
-   end,
-
-   -- Massacre
-   function()
-      des.room({ type = "themed",
-                 contents = function()
-                    local mon = { "apprentice", "warrior", "ninja", "thug",
-                                  "hunter", "acolyte", "abbot", "page",
-                                  "attendant", "neanderthal", "chieftain",
-                                  "student", "wizard", "valkyrie", "tourist",
-                                  "samurai", "rogue", "ranger", "priestess",
-                                  "priest", "monk", "knight", "healer",
-                                  "cavewoman", "caveman", "barbarian",
-                                  "archeologist" };
-                    shuffle(mon);
-                    for i = 1, d(5,5) do
-                       if (percent(10)) then shuffle(mon); end
-                       des.object({ id = "corpse", montype = mon[1] });
-                    end
-                 end
-      });
-   end,
+   {
+      frequency = 2,
+      contents = function()
+         des.room({ type = "themed", filled = 1, contents = themeroom_fill });
+      end
+   },
 
    -- Pillars
    function()
@@ -198,70 +243,6 @@ themerooms = {
       });
    end,
 
-   -- Statuary
-   function()
-      des.room({ type = "themed",
-                 contents = function()
-                    for i = 1, d(5,5) do
-                       des.object({ id = "statue" });
-                    end
-                    for i = 1, d(3) do
-                       des.trap("statue");
-                    end
-                 end
-      });
-   end,
-
-   -- Light source
-   function()
-      des.room({ type = "themed", lit = 0,
-                 contents = function()
-                    des.object({ id = "oil lamp", lit = true });
-                 end
-      });
-   end,
-
-   -- Temple of the gods
-   function()
-      des.room({ type = "themed",
-                 contents = function()
-                    des.altar({ align = align[1] });
-                    des.altar({ align = align[2] });
-                    des.altar({ align = align[3] });
-                 end
-      });
-   end,
-
-   -- Ghost of an Adventurer
-   function()
-      des.room({ type = "themed", lit = 0,
-                 contents = function(rm)
-                    local px = nh.rn2(rm.width);
-                    local py = nh.rn2(rm.height);
-                    des.monster({ id = "ghost", asleep = true, waiting = true, coord = {px,py} });
-                    if percent(65) then
-                       des.object({ id = "dagger", coord = {px,py}, buc = "not-blessed" });
-                    end
-                    if percent(55) then
-                       des.object({ class = ")", coord = {px,py}, buc = "not-blessed" });
-                    end
-                    if percent(45) then
-                       des.object({ id = "bow", coord = {px,py}, buc = "not-blessed" });
-                       des.object({ id = "arrow", coord = {px,py}, buc = "not-blessed" });
-                    end
-                    if percent(65) then
-                       des.object({ class = "[", coord = {px,py}, buc = "not-blessed" });
-                    end
-                    if percent(20) then
-                       des.object({ class = "=", coord = {px,py}, buc = "not-blessed" });
-                    end
-                    if percent(20) then
-                       des.object({ class = "?", coord = {px,py}, buc = "not-blessed" });
-                    end
-                 end
-      });
-   end,
-
    -- Mausoleum
    function()
       des.room({ type = "themed", w = 5 + nh.rn2(3)*2, h = 5 + nh.rn2(3)*2,
@@ -310,7 +291,7 @@ themerooms = {
 |......|
 |......|
 |......|
---------]], contents = function(m) des.region({ region={1,1,3,3}, type="ordinary", irregular=true, filled=1 }); end });
+--------]], contents = function(m) filler_region(1,1); end });
    end,
 
    -- L-shaped, rot 1
@@ -323,7 +304,7 @@ xxx|...|
 |......|
 |......|
 |......|
---------]], contents = function(m) des.region({ region={5,1,5,3}, type="ordinary", irregular=true, filled=1 }); end });
+--------]], contents = function(m) filler_region(5,1); end });
    end,
 
    -- L-shaped, rot 2
@@ -336,7 +317,7 @@ xxx|...|
 ----...|
 xxx|...|
 xxx|...|
-xxx-----]], contents = function(m) des.region({ region={1,1,2,2}, type="ordinary", irregular=true, filled=1 }); end });
+xxx-----]], contents = function(m) filler_region(1,1); end });
    end,
 
    -- L-shaped, rot 3
@@ -349,7 +330,7 @@ xxx-----]], contents = function(m) des.region({ region={1,1,2,2}, type="ordinary
 |...----
 |...|xxx
 |...|xxx
------xxx]], contents = function(m) des.region({ region={1,1,2,2}, type="ordinary", irregular=true, filled=1 }); end });
+-----xxx]], contents = function(m) filler_region(1,1); end });
    end,
 
    -- Blocked center
@@ -371,7 +352,7 @@ if (percent(30)) then
    shuffle(terr);
    des.replace_terrain({ region = {1,1, 9,9}, fromterrain = "L", toterrain = terr[1] });
 end
-des.region({ region={1,1,2,2}, type="ordinary", irregular=true, filled=1 });
+filler_region(1,1);
 end });
    end,
 
@@ -384,7 +365,7 @@ x--.--x
 |.....|
 --...--
 x--.--x
-xx---xx]], contents = function(m) des.region({ region={3,3,3,3}, type="ordinary", irregular=true, filled=1 }); end });
+xx---xx]], contents = function(m) filler_region(3,3); end });
    end,
 
    -- Circular, medium
@@ -398,7 +379,7 @@ x--...--x
 |.......|
 --.....--
 x--...--x
-xx-----xx]], contents = function(m) des.region({ region={4,4,4,4}, type="ordinary", irregular=true, filled=1 }); end });
+xx-----xx]], contents = function(m) filler_region(4,4); end });
    end,
 
    -- Circular, big
@@ -414,7 +395,7 @@ x-.......-x
 --.......--
 x-.......-x
 x---...---x
-xxx-----xxx]], contents = function(m) des.region({ region={5,5,5,5}, type="ordinary", irregular=true, filled=1 }); end });
+xxx-----xxx]], contents = function(m) filler_region(5,5); end });
    end,
 
    -- T-shaped
@@ -427,7 +408,7 @@ xxx|...|xxx
 |.........|
 |.........|
 |.........|
------------]], contents = function(m) des.region({ region={5,5,5,5}, type="ordinary", irregular=true, filled=1 }); end });
+-----------]], contents = function(m) filler_region(5,5); end });
    end,
 
    -- T-shaped, rot 1
@@ -443,7 +424,7 @@ xxx|...|xxx
 |...----
 |...|xxx
 |...|xxx
------xxx]], contents = function(m) des.region({ region={2,2,2,2}, type="ordinary", irregular=true, filled=1 }); end });
+-----xxx]], contents = function(m) filler_region(2,2); end });
    end,
 
    -- T-shaped, rot 2
@@ -456,7 +437,7 @@ xxx|...|xxx
 ----...----
 xxx|...|xxx
 xxx|...|xxx
-xxx-----xxx]], contents = function(m) des.region({ region={2,2,2,2}, type="ordinary", irregular=true, filled=1 }); end });
+xxx-----xxx]], contents = function(m) filler_region(2,2); end });
    end,
 
    -- T-shaped, rot 3
@@ -472,7 +453,7 @@ xxx|...|
 ----...|
 xxx|...|
 xxx|...|
-xxx-----]], contents = function(m) des.region({ region={5,5,5,5}, type="ordinary", irregular=true, filled=1 }); end });
+xxx-----]], contents = function(m) filler_region(5,5); end });
    end,
 
    -- S-shaped
@@ -488,7 +469,7 @@ xxx-----]], contents = function(m) des.region({ region={5,5,5,5}, type="ordinary
 ----...|
 xxx|...|
 xxx|...|
-xxx-----]], contents = function(m) des.region({ region={2,2,2,2}, type="ordinary", irregular=true, filled=1 }); end });
+xxx-----]], contents = function(m) filler_region(2,2); end });
    end,
 
    -- S-shaped, rot 1
@@ -501,7 +482,7 @@ xxx|......|
 |......----
 |......|xxx
 |......|xxx
---------xxx]], contents = function(m) des.region({ region={5,5,5,5}, type="ordinary", irregular=true, filled=1 }); end });
+--------xxx]], contents = function(m) filler_region(5,5); end });
    end,
 
    -- Z-shaped
@@ -517,7 +498,7 @@ xxx|...|
 |...----
 |...|xxx
 |...|xxx
------xxx]], contents = function(m) des.region({ region={5,5,5,5}, type="ordinary", irregular=true, filled=1 }); end });
+-----xxx]], contents = function(m) filler_region(5,5); end });
    end,
 
    -- Z-shaped, rot 1
@@ -530,7 +511,7 @@ xxx|...|
 ----......|
 xxx|......|
 xxx|......|
-xxx--------]], contents = function(m) des.region({ region={2,2,2,2}, type="ordinary", irregular=true, filled=1 }); end });
+xxx--------]], contents = function(m) filler_region(2,2); end });
    end,
 
    -- Cross
@@ -546,7 +527,7 @@ xxx|...|xxx
 ----...----
 xxx|...|xxx
 xxx|...|xxx
-xxx-----xxx]], contents = function(m) des.region({ region={6,6,6,6}, type="ordinary", irregular=true, filled=1 }); end });
+xxx-----xxx]], contents = function(m) filler_region(6,6); end });
    end,
 
    -- Four-leaf clover
@@ -562,7 +543,7 @@ xx|.....|xx
 |.........|
 |...---...|
 |...|x|...|
------x-----]], contents = function(m) des.region({ region={6,6,6,6}, type="ordinary", irregular=true, filled=1 }); end });
+-----x-----]], contents = function(m) filler_region(6,6); end });
    end,
 
    -- Water-surrounded vault
@@ -639,7 +620,18 @@ end });
 
 };
 
-function is_eligible(room)
+
+function filler_region(x, y)
+   local rmtyp = "ordinary";
+   local func = nil;
+   if (percent(30)) then
+      rmtyp = "themed";
+      func = themeroom_fill;
+   end
+   des.region({ region={x,y,x,y}, type=rmtyp, irregular=true, filled=1, contents = func });
+end
+
+function is_eligible(room, mkrm)
    local t = type(room);
    local diff = nh.level_difficulty();
    if (t == "table") then
@@ -648,6 +640,9 @@ function is_eligible(room)
       elseif (room.maxdiff ~= nil and diff > room.maxdiff) then
          return false
       end
+      if (mkrm ~= nil and room.eligible ~= nil) then
+         return room.eligible(mkrm);
+      end
    elseif (t == "function") then
       -- functions currently have no constraints
    end
@@ -660,7 +655,7 @@ function themerooms_generate()
    for i = 1, #themerooms do
       -- Reservoir sampling: select one room from the set of eligible rooms,
       -- which may change on different levels because of level difficulty.
-      if is_eligible(themerooms[i]) then
+      if is_eligible(themerooms[i], nil) then
          local this_frequency;
          if (type(themerooms[i]) == "table" and themerooms[i].frequency ~= nil) then
             this_frequency = themerooms[i].frequency;
@@ -682,3 +677,32 @@ function themerooms_generate()
       themerooms[pick]();
    end
 end
+
+function themeroom_fill(rm)
+   local pick = 1;
+   local total_frequency = 0;
+   for i = 1, #themeroom_fills do
+      -- Reservoir sampling: select one room from the set of eligible rooms,
+      -- which may change on different levels because of level difficulty.
+      if is_eligible(themeroom_fills[i], rm) then
+         local this_frequency;
+         if (type(themeroom_fills[i]) == "table" and themeroom_fills[i].frequency ~= nil) then
+            this_frequency = themeroom_fills[i].frequency;
+         else
+            this_frequency = 1;
+         end
+         total_frequency = total_frequency + this_frequency;
+         -- avoid rn2(0) if a room has freq 0
+         if this_frequency > 0 and nh.rn2(total_frequency) < this_frequency then
+            pick = i;
+         end
+      end
+   end
+
+   local t = type(themeroom_fills[pick]);
+   if (t == "table") then
+      themeroom_fills[pick].contents(rm);
+   elseif (t == "function") then
+      themeroom_fills[pick](rm);
+   end
+end
diff --git a/doc/lua.adoc b/doc/lua.adoc
index e0959480d..8b614bb4d 100644
--- a/doc/lua.adoc
+++ b/doc/lua.adoc
@@ -1070,6 +1070,20 @@ Example:
  local coord = selection.rndcoord(sel);
  local coord = selection.rndcoord(sel, 1);
 
+
+=== room
+
+Create a selection of locations inside the (current) room.
+
+Example:
+
+ des.room({ type = "ordinary", contents = function(rm)
+   local sel = selection.room();
+   des.terrain(sel, "I");
+ end
+ });
+
+
 === set
 
 Set the value for location (x,y) in the selection.
diff --git a/include/extern.h b/include/extern.h
index 32b88d989..bbb337376 100644
--- a/include/extern.h
+++ b/include/extern.h
@@ -2612,6 +2612,7 @@ extern boolean get_coord(lua_State *, int, lua_Integer *, lua_Integer *);
 extern void cvt_to_abscoord(coordxy *, coordxy *);
 extern void cvt_to_relcoord(coordxy *, coordxy *);
 extern int nhl_abs_coord(lua_State *);
+extern struct selectionvar *selection_from_mkroom(struct mkroom *);
 extern void update_croom(void);
 extern const char *get_trapname_bytype(int);
 extern void l_register_des(lua_State *);
diff --git a/src/nhlsel.c b/src/nhlsel.c
index 085ac5996..96ed226d2 100644
--- a/src/nhlsel.c
+++ b/src/nhlsel.c
@@ -17,6 +17,7 @@ static int l_selection_getpoint(lua_State *);
 static int l_selection_setpoint(lua_State *);
 static int l_selection_filter_percent(lua_State *);
 static int l_selection_rndcoord(lua_State *);
+static int l_selection_room(lua_State *);
 static int l_selection_getbounds(lua_State *);
 static boolean params_sel_2coords(lua_State *, struct selectionvar **,
                                   coordxy *, coordxy *, coordxy *, coordxy *);
@@ -383,6 +384,28 @@ l_selection_rndcoord(lua_State *L)
     return 1;
 }
 
+/* local s = selection.room(); */
+static int
+l_selection_room(lua_State *L)
+{
+    struct selectionvar *sel;
+    int argc = lua_gettop(L);
+    struct mkroom *croom = NULL;
+
+    if (argc == 1) {
+        int i = luaL_checkinteger(L, -1);
+
+        croom = (i >= 0 && i < g.nroom) ? &g.rooms[i] : NULL;
+    }
+
+    sel = selection_from_mkroom(croom);
+
+    l_selection_push_copy(L, sel);
+    selection_free(sel, TRUE);
+
+    return 1;
+}
+
 /* local rect = sel:bounds(); */
 static int
 l_selection_getbounds(lua_State *L)
@@ -899,6 +922,7 @@ static const struct luaL_Reg l_selection_methods[] = {
     { "gradient", l_selection_gradient },
     { "iterate", l_selection_iterate },
     { "bounds", l_selection_getbounds },
+    { "room", l_selection_room },
     { NULL, NULL }
 };
 
diff --git a/src/sp_lev.c b/src/sp_lev.c
index a546bc6e0..959cab09c 100644
--- a/src/sp_lev.c
+++ b/src/sp_lev.c
@@ -6056,7 +6056,8 @@ lspo_region(lua_State *L)
             lua_getfield(L, 1, "contents");
             if (lua_type(L, -1) == LUA_TFUNCTION) {
                 lua_remove(L, -2);
-                if (nhl_pcall(L, 0, 0)){
+                l_push_mkroom_table(L, troom);
+                if (nhl_pcall(L, 1, 0)){
                     impossible("Lua error: %s", lua_tostring(L, -1));
                 }
             } else
@@ -6664,6 +6665,25 @@ TODO: g.coder->croom needs to be updated
     return 0;
 }
 
+struct selectionvar *
+selection_from_mkroom(struct mkroom *croom)
+{
+    struct selectionvar *sel = selection_new();
+    coordxy x, y;
+
+    if (!croom && g.coder && g.coder->croom)
+        croom = g.coder->croom;
+    if (!croom)
+        return sel;
+
+    for (y = croom->ly; y <= croom->hy; y++)
+        for (x = croom->lx; x <= croom->hx; x++)
+            if (isok(x, y) && !levl[x][y].edge
+                && levl[x][y].roomno == (croom - g.rooms) + ROOMOFFSET)
+                selection_setpoint(x, y, sel, 1);
+    return sel;
+}
+
 void
 update_croom(void)
 {