diff --git a/src/internal.cpp b/src/internal.cpp
index c4dd5ed..e6ff8e8 100644
--- a/src/internal.cpp
+++ b/src/internal.cpp
@@ -85,4 +85,16 @@ namespace vkvm {
         unlockSharedMemory();
     }
 
+    auto getRegisteredProcesses(EventType eventType) -> std::vector<int> {
+        std::vector<int> result;
+        auto ivt = getInterruptTable();
+        for(int i = 0; i < impl.interruptEntrysPerEventType;i++){
+            auto &entry= ivt[eventType * impl.interruptEntrysPerEventType + i];
+            if (entry.pid != 0) {
+                result.push_back(entry.pid);
+            }
+        }
+        return result;
+    }
+
 }
diff --git a/src/internal.hpp b/src/internal.hpp
index e1b5ea2..a84676a 100644
--- a/src/internal.hpp
+++ b/src/internal.hpp
@@ -126,6 +126,12 @@ constexpr int keyboardBufferSize = 16;
  */
     auto buttonPressed(KeyCode keyCode) -> void;
 
+/**
+ * get registered Prosesses for a given event type.
+ * @param eventType.
+ */
+    auto getRegisteredProcesses(EventType eventType) -> std::vector<int>;
+
 // Shared Memory Layout
 // --------------------------------------------------------------------
 // struct ControlRegisters
diff --git a/src/vkvm.cpp b/src/vkvm.cpp
index 331ba6c..d48d36b 100644
--- a/src/vkvm.cpp
+++ b/src/vkvm.cpp
@@ -63,6 +63,9 @@ namespace vkvm {
     }
 
     auto setPixel(int x, int y, Color color) -> bool {
+        if(x < 0 || y < 0){
+            return false;
+        }
         if (x > getWidth() || y > getHeight()) {
             return false;
         }