diff --git a/CMakeLists.txt b/CMakeLists.txt
index 15be850..8a2001f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -25,7 +25,7 @@ include_directories(deps/inotify)
 include_directories(deps/handmademath)
 
 include_directories(${PROJECT_SOURCE_DIR})
-add_executable(zinnia src/main.cpp src/gui.cpp src/project.cpp
+add_executable(zinnia src/main.cpp src/geom.cpp src/gui/gui.cpp src/project.cpp
 	src/shaders.cpp
 	${IMGUI_SOURCE})
 
diff --git a/src/geom.cpp b/src/geom.cpp
new file mode 100644
index 0000000..b4dffbb
--- /dev/null
+++ b/src/geom.cpp
@@ -0,0 +1,11 @@
+#include "geom.h"
+
+std::ostream &operator<<(std::ostream &os, const ImVec2 &vec) {
+  os << "[" << vec.x << ", " << vec.y << "]";
+  return os;
+}
+
+std::ostream &operator<<(std::ostream &os, const Rect &rect) {
+  os << "Rect { pos: " << rect.pos << ", size: " << rect.size << " }";
+  return os;
+}
diff --git a/src/geom.h b/src/geom.h
new file mode 100644
index 0000000..cbbb0e0
--- /dev/null
+++ b/src/geom.h
@@ -0,0 +1,30 @@
+#pragma once
+
+#define IMGUI_DEFINE_MATH_OPERATORS
+#include <imgui.h>
+#include <imgui_internal.h>
+#include <sstream>
+
+class Rect {
+public:
+    Rect(ImVec2 pos, ImVec2 size) : pos(pos), size(size) {}
+    Rect(float x, float y, float w, float h) : pos(x, y), size(w, h) {}
+
+    ImVec2 pos;
+    ImVec2 size;
+
+    float top() const    { return pos.y; }
+    float left() const   { return pos.x; }
+    float bottom() const { return pos.y + size.y; }
+    float right() const  { return pos.x + size.x; }
+
+    bool intersects(const Rect &other) {
+        return this->left() < other.right() &&
+               this->right() > other.left() &&
+               this->top() < other.bottom() &&
+               this->bottom() > other.top();
+    }
+};
+
+std::ostream &operator<<(std::ostream &os, const ImVec2 &vec);
+std::ostream &operator<<(std::ostream &os, const Rect &rect);
diff --git a/src/main.cpp b/src/main.cpp
index 4506d8e..4b2bb2e 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -8,6 +8,7 @@
 #include <GLFW/glfw3.h>
 
 #include "gui.h"
+#include "geom.h"
 #include "state.h"
 #include "notify.h"