Stop using WindowSize and actually make use of event window size, provide default

src/basic/math.cpp

@@ -110,6 +110,11 @@ Vec2 operator/=(Vec2 &a, float b) { a = a / b; return a; }
 
 // clang-format on
 
+Rect2 Rect0Size(float x, float y) {
+    Rect2 rect = {0, 0, x, y};
+    return rect;
+}
+
 Rect2 Rect2FromSize(Vec2 pos, Vec2 size) {
     Rect2 result = {};
     result.min   = pos;

src/basic/math_int.cpp

@@ -73,6 +73,11 @@ Vec2I operator/=(Vec2I &a, Int b) { a = a / b; return a; }
 
 // clang-format on
 
+Rect2I RectI0Size(Int x, Int y) {
+    Rect2I rect = {0, 0, x, y};
+    return rect;
+}
+
 Rect2I Rect2IFromSize(Vec2I pos, Vec2I size) {
     Rect2I result = {};
     result.min    = pos;