diff --git a/src/doompanning.cc b/src/doompanning.cc
index b702051..897da53 100644
--- a/src/doompanning.cc
+++ b/src/doompanning.cc
@@ -8,6 +8,7 @@
 #include <array>
 #include <cerrno>
 #include <cstdlib>
+#include <cstring>
 #include <thread>
 #include <type_traits>
 #include <vector>
@@ -20,22 +21,64 @@
 #include "dp_common.h"
 #include "dp_util.hpp"
 
+#if DoomBytesPerPixel == 3
+static const u32 DoomSdlTexturePixelFormat = SDL_PIXELFORMAT_RGB888;
+#elif DoomBytesPerPixel == 4
+static const u32 DoomSdlTexturePixelFormat = SDL_PIXELFORMAT_ARGB8888;
+#else
+#error Unhandled DoomBytesPerPixel value. Which SDL_PIXELFORMAT to use?
+#endif
+
+
 void dp_sdl_fatal(const char *const msg)
 {
     log_fatal("%s: %s", msg, SDL_GetError());
     abort();
 }
 
+void dp_sdl_error(const char *const msg)
+{
+    log_error("%s: %s", msg, SDL_GetError());
+}
+
 struct DoomState
 {
+    // So easy to get this wrong and destroy the texture by accident. Cleanup is
+    // now done in check_on_dooms() before erasing the state. Enabling this code
+    // still works though.
+#if 0
+    DoomState() = default;
+    ~DoomState()
+    {
+        log_trace("~DoomState");
+        if (texture)
+            SDL_DestroyTexture(texture);
+    }
+    DoomState(const DoomState &) = delete;
+    DoomState &operator=(const DoomState &) = delete;
+
+    DoomState(DoomState &&o)
+        : DoomState()
+    {
+        *this = std::move(o);
+    }
+
+    DoomState &operator=(DoomState &&o)
+    {
+        std::swap(id, o.id);
+        std::swap(state, o.state);
+        std::swap(tLastActive, o.tLastActive);
+        std::swap(texture, o.texture);
+        return *this;
+    }
+#endif
+
     doomid_t id = 0;
     DP_DoomState state = DP_DS_Unknown;
+    std::chrono::steady_clock::time_point tLastActive;
     SDL_Texture *texture = nullptr;
 };
 
-static_assert(std::is_trivially_copyable<DoomState>::value,
-    "DoomState must be a trivially copyable type");
-
 struct ControllerContext
 {
     nng_socket pub;
@@ -47,6 +90,10 @@ struct ControllerContext
     ExampleAppLog appLog;
     int columns = 4;
     std::array<u8, DoomScreenWidth * DoomScreenHeight * DoomBytesPerPixel> pixelBuffer;
+    float scaleFactor = 1.0;
+    s32 offsetX = 0;
+    s32 offsetY = 0;
+    bool isMousePanning = false;
 };
 
 struct ControllerActions
@@ -59,29 +106,22 @@ struct ControllerActions
 
 void spawn_doom_posix_spawn(ControllerContext &ctx)
 {
-    DoomState ds;
-
+    (void) ctx;
     const char *const argv[] = { DOOM_EXECUTABLE, nullptr };
 
     // TODO: Close stdin and stdout? Leave them open for now to see the logging
     // output.
-    // FIXME: SDL is not able to init its sound system in the doomchild. Try to ask
-    // it if it's already initialized and skip if true.
-    if (auto err = posix_spawn(&ds.id, DOOM_EXECUTABLE, nullptr, nullptr,
+    // FIXME: SDL is not able to init its sound system in the doomchild. Try
+    // something similar to xdg-open where a doomgrandchild execvp()s the doom.
+    pid_t pid;
+    if (auto err = posix_spawn(&pid, DOOM_EXECUTABLE, nullptr, nullptr,
         const_cast<char *const *>(argv), nullptr))
     {
         log_error("Could not spawn doom: %s", strerror(err));
         return;
     }
 
-    ds.texture = SDL_CreateTexture(ctx.renderer, SDL_PIXELFORMAT_RGB888,
-        SDL_TEXTUREACCESS_STREAMING, DoomScreenWidth, DoomScreenHeight);
-
-    if (!ds.texture)
-        dp_sdl_fatal("SDL_CreateTexture");
-
-    log_info("Spawned new doom, pid=%d", ds.id);
-    ctx.dooms.emplace_back(ds);
+    log_info("Spawned new doom, pid=%d", pid);
 }
 
 inline void spawn_doom(ControllerContext &ctx)
@@ -105,15 +145,6 @@ void end_all_dooms(ControllerContext &ctx)
         dp_nng_fatal("ctrl/sendmsg", res);
 }
 
-void signal_all_dooms(ControllerContext &ctx, int signum)
-{
-    std::for_each(std::begin(ctx.dooms), std::end(ctx.dooms),
-        [signum] (const auto &ds)
-        {
-            kill(ds.id, signum);
-        });
-}
-
 void perform_actions(ControllerContext &ctx, const ControllerActions &actions)
 {
     if (actions.doomsToSpawn)
@@ -130,8 +161,12 @@ void perform_actions(ControllerContext &ctx, const ControllerActions &actions)
     }
 }
 
+inline auto dp_now() { return std::chrono::steady_clock::now(); }
+inline auto dp_elapsed(const std::chrono::steady_clock::time_point &tStart) { return tStart - dp_now(); }
+
 void check_on_dooms(ControllerContext &ctx)
 {
+    #if 0
     pid_t pid = 0;
 
     // This works for dooms forked from the controller, not for externally
@@ -158,6 +193,18 @@ void check_on_dooms(ControllerContext &ctx)
             }
         }
     } while (pid > 0);
+    #else
+    const auto sz0 = ctx.dooms.size();
+    auto eb = std::remove_if(std::begin(ctx.dooms), std::end(ctx.dooms), [] (const auto &ds) { return ds.state == DP_DS_Endoom; });
+    if (eb != std::end(ctx.dooms))
+    {
+        auto count = std::distance(eb, std::end(ctx.dooms));
+        std::for_each(eb, std::end(ctx.dooms), [] (auto &ds) { SDL_DestroyTexture(ds.texture); ds.texture = nullptr; });
+        ctx.dooms.erase(eb, std::end(ctx.dooms));
+        const auto sz1 = ctx.dooms.size();
+        log_info("Erased %zu dooms which were in Endoom state. doomcount before=%zu, after=%zu", count, sz0, sz1);
+    }
+    #endif
 }
 
 void do_networking(ControllerContext &ctx)
@@ -168,15 +215,12 @@ void do_networking(ControllerContext &ctx)
 
     // Limit the max time we spend doing network stuff.
     static const auto MaxNetworkingTime = std::chrono::milliseconds(10);
-    auto tStart = std::chrono::steady_clock::now();
+    auto tStart = dp_now();
 
     while (true)
     {
-        if (auto elapsed = std::chrono::steady_clock::now() - tStart;
-            elapsed >= MaxNetworkingTime)
-        {
+        if (auto elapsed = dp_elapsed(tStart); elapsed >= MaxNetworkingTime)
             break;
-        }
 
         nng_msg *msg = nullptr;
 
@@ -193,28 +237,52 @@ void do_networking(ControllerContext &ctx)
         {
             auto msgDoomState = DP_NNG_BODY_AS(msg, MsgDoomState);
 
-            // Check if we know this doom. If it was externally started register
-            // it in ctx.dooms.
+            // Check if we know this doom and register it if we don't.
             auto pid = msgDoomState->doomId;
             auto dit = find_in_container(ctx.dooms, [pid] (const auto &ds) { return ds.id == pid; });
 
             if (dit != std::end(ctx.dooms))
             {
                 dit->state = msgDoomState->doomState;
+                dit->tLastActive = dp_now();
             }
             else
             {
                 DoomState ds;
                 ds.id = pid;
                 ds.state = msgDoomState->doomState;
-                ds.texture = SDL_CreateTexture(ctx.renderer, SDL_PIXELFORMAT_RGB888,
-                                               SDL_TEXTUREACCESS_STREAMING, DoomScreenWidth, DoomScreenHeight);
+                ds.tLastActive = dp_now();
+                ds.texture = SDL_CreateTexture(
+                    ctx.renderer, DoomSdlTexturePixelFormat,
+                    SDL_TEXTUREACCESS_STREAMING, DoomScreenWidth, DoomScreenHeight);
 
                 if (!ds.texture)
                     dp_sdl_fatal("SDL_CreateTexture");
 
-                log_info("Registered external doom, pid=%d", ds.id);
-                ctx.dooms.emplace_back(ds);
+                {
+                    u32 format = 0;
+                    int access = 0;
+                    int w = 0;
+                    int h = 0;
+                    if (SDL_QueryTexture(ds.texture, &format, &access, &w, &h))
+                        dp_sdl_fatal("SDL_QueryTexture");
+
+                    log_debug("texture info (wanted, got): format=(%u, %u), access=(%d, %d), w=(%d, %d), h=(%d, %d)",
+                        DoomSdlTexturePixelFormat, format,
+                        SDL_TEXTUREACCESS_STREAMING, access,
+                        DoomScreenWidth, w,
+                        DoomScreenHeight, h
+                    );
+
+                    assert(format == DoomSdlTexturePixelFormat);
+                    assert(access == SDL_TEXTUREACCESS_STREAMING);
+                    assert(w == DoomScreenWidth);
+                    assert(h == DoomScreenHeight);
+
+                }
+
+                log_info("Registered new doom (pid=%d)", ds.id);
+                ctx.dooms.emplace_back(std::move(ds));
             }
 
             if (msgDoomState->doomState == DP_DS_Ready)
@@ -229,10 +297,42 @@ void do_networking(ControllerContext &ctx)
             if (dit != std::end(ctx.dooms))
             {
                 auto &ds = *dit;
-                SDL_UpdateTexture(ds.texture, nullptr, msgDoomFrame->frame, DoomFramePitch);
+                ds.tLastActive = dp_now();
+
+                const u8 *sourcePixels = msgDoomFrame->frame;
+
+                #if 0
+                // FIXME: buggy. black screen with tiny bar on top
+                //log_trace("Texture update for doom (pid=%d, texture=%p)", ds.id, ds.texture);
+
+                u8 *destPixels = nullptr;
+                int texturePitch = 0;
+
+                if (SDL_LockTexture(ds.texture, nullptr, reinterpret_cast<void **>(&destPixels), &texturePitch))
+                    dp_sdl_fatal("SDL_LockTexture");
+
+                // When using 3 bytes per pixel (960 bytes per row), SDL yields
+                // a pitch of 1280 on my machine. This is likely done to get
+                // good alignment.
+                assert(DoomFramePitch <= texturePitch);
+
+                for (size_t row=0; row<DoomScreenHeight; ++row)
+                {
+                    u8 *destRow = destPixels + row + texturePitch;
+                    const u8 *sourceRow = sourcePixels + row * DoomFramePitch;
+                    std::memcpy(destRow, sourceRow, DoomFramePitch);
+                }
+
+                SDL_UnlockTexture(ds.texture);
+                #else
+                // FIXME: buggy. sometimes crashes with DoomBytesPerPixel=3, hasn't crashed with DoomBytesPerPixel=4 yet.
+                // In the latter case SDL texture pitch equals DoomFramePitch...
+                if (SDL_UpdateTexture(ds.texture, nullptr, sourcePixels, DoomFramePitch))
+                    dp_sdl_fatal("SDL_UpdateTexture");
+                #endif
             }
             else
-                log_warn("Received DoomFrame from unregistered doom, pid=%d", pid);
+                log_trace("Received DoomFrame from unregistered doom (pid=%d)", pid);
         }
 
         nng_msg_free(msg);
@@ -264,8 +364,7 @@ void final_cleanup(ControllerContext &ctx)
 
     if (!ctx.dooms.empty())
     {
-        log_warn("final cleanup: terminating all %zu remaining dooms", ctx.dooms.size());
-        signal_all_dooms(ctx, SIGTERM);
+        log_warn("final cleanup: %zu dooms remain", ctx.dooms.size());
     }
 }
 
@@ -375,6 +474,7 @@ void DrawRectangle(OffscreenBuffer *buffer,
 
 void render_dooms(ControllerContext &ctx)
 {
+    #if 0
     OffscreenBuffer buffer =
     {
         DoomScreenWidth,
@@ -384,31 +484,31 @@ void render_dooms(ControllerContext &ctx)
         DoomBytesPerPixel
     };
 
-    DrawRectangle(&buffer, 0, 0, 10, 10, { 1, 0, 0, 1 }); // top-left red
+    DrawRectangle(&buffer, 0, 0, 10, 10, { 1, 0, 0, 1 });
     DrawRectangle(&buffer, 0, buffer.height-10, 10, buffer.height, { 0, 1, 0, 1 });
     DrawRectangle(&buffer, buffer.width-10, buffer.height-10, buffer.width, buffer.height, { 0, 0, 1, 1 });
     DrawRectangle(&buffer, buffer.width-10, 0, buffer.width, 10, { 0.840, 0.0168, 0.717, 1 });
+    #endif
 
-    //DrawRectangle(&buffer, buffer.width-10, 0, buffer.width, 10, { 0.0, 1.0, 0.0, 1.0 }); // top-right green
+    SDL_Rect destRect = { ctx.offsetX, ctx.offsetY, DoomScreenWidth, DoomScreenHeight };
+
+    destRect.w *= ctx.scaleFactor;
+    destRect.h *= ctx.scaleFactor;
 
-    SDL_Rect destRect = {0, 0, buffer.width, buffer.height};
     const size_t doomCount = ctx.dooms.size();
 
     for (size_t i=0; i<doomCount; ++i)
     {
         if (i != 0 && i % ctx.columns == 0)
         {
-            destRect.x = 0;
-            destRect.y += buffer.height;
+            destRect.x = ctx.offsetX;
+            destRect.y += destRect.h;
         }
 
         auto &ds = ctx.dooms.at(i);
         auto texture = ds.texture;
-        assert(texture);
-        //SDL_UpdateTexture(texture, nullptr, buffer.pixels, buffer.width * buffer.BytesPerPixel);
         SDL_RenderCopy(ctx.renderer, texture, nullptr, &destRect);
-
-        destRect.x += buffer.width;
+        destRect.x += destRect.w;
     }
 }
 
@@ -483,15 +583,17 @@ ControllerActions run_ui(ControllerContext &ctx)
     ImGui::PushItemWidth(ImGui::GetFontSize() * -16); // affects stuff like slider widths
 
     ImGui::SliderInt("Layout columns##columns", &ctx.columns, 1, 32, "%d", ImGuiSliderFlags_AlwaysClamp);
+    ImGui::SliderFloat("Doom scale", &ctx.scaleFactor, 0.1, 10, "%.3f", ImGuiSliderFlags_AlwaysClamp);
 
     ImGui::SliderInt("##dooms", &doomsToSpawn, 1, 256, "%d", ImGuiSliderFlags_AlwaysClamp | ImGuiSliderFlags_Logarithmic);
     aprintf(strbuf, "Spawn %d more doom%s###spawnmore", doomsToSpawn, doomsToSpawn > 1 ? "s" : "");
     if (ImGui::SameLine(); ImGui::Button(strbuf.data()))
         result.doomsToSpawn = doomsToSpawn;
 
-    if (ImGui::Button("End all Dooms"))
+    if (ImGui::Button("End all dooms"))
         result.endAllDooms = true;
 
+
     ImGui::PopItemWidth();
     ImGui::End();
 
@@ -507,6 +609,9 @@ int doom_controller_loop(ControllerContext &ctx)
     while (!ctx.quit)
     {
         SDL_Event event;
+        auto &io = ImGui::GetIO();
+        s32 mouseWheel = 0.0;
+
         while (SDL_PollEvent(&event))
         {
             ImGui_ImplSDL2_ProcessEvent(&event);
@@ -520,18 +625,69 @@ int doom_controller_loop(ControllerContext &ctx)
             {
                 ctx.quit = true;
             }
+
+            if (event.type == SDL_MOUSEWHEEL)
+                mouseWheel += event.wheel.y;
         }
 
         // Process input events not consumed by ImGui
-        if (auto &io = ImGui::GetIO();
-            !io.WantCaptureKeyboard)
+        if (!io.WantCaptureKeyboard)
         {
+            // TODO: make scaling scale with the current scale factor
+            static const float ScaleStep = 0.01f;
+            s32 PanStep = io.KeyCtrl ? 10 : 2;
+
             if (io.KeyCtrl && ImGui::IsKeyDown(ImGuiKey_Q))
-            {
                 ctx.quit = true;
+
+            if (ImGui::IsKeyDown(ImGuiKey_Equal))
+                ctx.scaleFactor += ScaleStep;
+            if (ImGui::IsKeyDown(ImGuiKey_Minus))
+                ctx.scaleFactor -= ScaleStep;
+            if (ImGui::IsKeyDown(ImGuiKey_0))
+                ctx.scaleFactor = 1.0;
+
+            if (ImGui::IsKeyDown(ImGuiKey_H))
+                ctx.offsetX -= PanStep;
+            if (ImGui::IsKeyDown(ImGuiKey_J))
+                ctx.offsetY += PanStep;
+            if (ImGui::IsKeyDown(ImGuiKey_K))
+                ctx.offsetY -= PanStep;
+            if (ImGui::IsKeyDown(ImGuiKey_L))
+                ctx.offsetX += PanStep;
+
+            if (ImGui::IsKeyDown(ImGuiKey_G))
+                ctx.offsetX = ctx.offsetY = 0;
+        }
+
+        static ImVec2 panStartPos;
+
+        if (!io.WantCaptureMouse)
+        {
+            ctx.scaleFactor += mouseWheel * 0.05;
+
+            if (ImGui::IsKeyPressed(ImGuiKey_MouseLeft, false))
+            {
+                panStartPos = io.MousePos;
+                ctx.isMousePanning = true;
             }
         }
 
+        if (ImGui::IsKeyReleased(ImGuiKey_MouseLeft))
+            ctx.isMousePanning = false;
+
+        if (ctx.isMousePanning)
+        {
+            auto curPos = io.MousePos;
+            auto dx = curPos.x - panStartPos.x;
+            auto dy = curPos.y - panStartPos.y;
+            ctx.offsetX += dx;
+            ctx.offsetY += dy;
+            panStartPos = curPos;
+        }
+
+        ctx.scaleFactor = std::clamp(ctx.scaleFactor, 0.1f, 10.0f);
+
         perform_actions(ctx, actions);
         check_on_dooms(ctx);
         do_networking(ctx);
@@ -603,7 +759,10 @@ int main(int argc, char *argv[])
     ImGui_ImplSDL2_InitForSDLRenderer(window, renderer);
     ImGui_ImplSDLRenderer_Init(renderer);
 
-    dp_nng_init_limits(1, 1, 1); // int ncpu_max, int pool_thread_limit_max, int resolv_thread_limit
+    //dp_nng_init_limits(1, 1, 1); // int ncpu_max, int pool_thread_limit_max, int resolv_thread_limit
+    //nng_set_ncpu_max(ncpu_max);
+    //nng_set_pool_thread_limit_max(pool_thread_limit_max);
+    nng_set_resolve_thread_max(1);
 
     ControllerContext ctx;
     ctx.pub = make_ctrl_pub(CtrlUrl);