Fix: ImDrawList:PushClipRectFullScreen() was missing (drop target outside the window clip rect crashed); CalcItemSize() no longer writes to the caller's size (by value like upstream; fixes BeginTable UserOuterSize), scalar _CalcItemSizeXY for internal callers; t_fixes covers both

build/ImGui.luau

@@ -6986,8 +6986,14 @@ end
 --- @param default_h float
 --- @return ImVec2
 function ImGui.CalcItemSize(size, default_w, default_h)
+    return ImVec2(ImGui._CalcItemSizeXY(size.x, size.y, default_w, default_h)) -- [Luau] 'size' is by value upstream: never written to
+end
+
+-- [Luau] scalar CalcItemSize(): callers that build 'size' themselves skip both ImVec2 allocations
+--- @return float, float
+function ImGui._CalcItemSizeXY(size_x, size_y, default_w, default_h)
     local avail_x, avail_y
-    if size.x < 0.0 or size.y < 0.0 then
+    if size_x < 0.0 or size_y < 0.0 then
         -- [Luau] scalar GetContentRegionAvail(), no temporary ImVec2
         local g = GImGui
         local window = g.CurrentWindow
@@ -6995,19 +7001,19 @@ function ImGui.CalcItemSize(size, default_w, default_h)
         avail_x = mx.x - window.DC.CursorPos.x; avail_y = mx.y - window.DC.CursorPos.y
     end
 
-    if size.x == 0.0 then
-        size.x = default_w
-    elseif size.x < 0.0 then
-        size.x = math.max(4.0, avail_x + size.x)  -- <-- size.x is negative here so we are subtracting
+    if size_x == 0.0 then
+        size_x = default_w
+    elseif size_x < 0.0 then
+        size_x = math.max(4.0, avail_x + size_x)  -- <-- size.x is negative here so we are subtracting
     end
 
-    if size.y == 0.0 then
-        size.y = default_h
-    elseif size.y < 0.0 then
-        size.y = math.max(4.0, avail_y + size.y)  -- <-- size.y is negative here so we are subtracting
+    if size_y == 0.0 then
+        size_y = default_h
+    elseif size_y < 0.0 then
+        size_y = math.max(4.0, avail_y + size_y)  -- <-- size.y is negative here so we are subtracting
     end
 
-    return size
+    return size_x, size_y
 end
 
 function ImGui.GetTextLineHeight()
@@ -34804,6 +34810,11 @@ function MT.ImDrawList:PushClipRect(cr_min, cr_max, intersect_with_current_clip_
     self:_OnChangedClipRect()
 end
 
+function MT.ImDrawList:PushClipRectFullScreen()
+    local cr = self._Data.ClipRectFullscreen
+    self:PushClipRect(ImVec2(cr.x, cr.y), ImVec2(cr.z, cr.w))
+end
+
 function MT.ImDrawList:PopClipRect()
     local stack = self._ClipRectStack
     assert(stack.Size > 0)
@@ -55064,6 +55075,7 @@ local IM_U32_MAX = UINT_MAX -- (0xFFFFFFFF)
 --- @param text_end? int
 --- @param flags?    ImGuiTextFlags
 local TextEx_bb = ImRect() -- [Luau] scratch, never escapes TextEx()
+local LAYOUT_ZERO_SIZE = ImVec2(0, 0) -- [Luau] shared read-only: ItemSize()/CalcItemSize() only read it
 
 @native
 function ImGui.TextEx(text, text_end, flags)
@@ -55264,7 +55276,7 @@ function ImGui.TextAligned(align_x, size_x, fmt, ...)
     local text = ImFormatString(fmt, ...)
     local text_end = #text + 1
     local text_size = ImGui.CalcTextSize(text, text_end)
-    size_x = ImGui.CalcItemSize(ImVec2(size_x, 0.0), 0.0, text_size.y).x
+    size_x = ImGui._CalcItemSizeXY(size_x, 0.0, 0.0, text_size.y)
 
     local pos = ImVec2(window.DC.CursorPos.x, window.DC.CursorPos.y + window.DC.CurrLineTextBaseOffset)
     local pos_max = ImVec2(pos.x + size_x, window.ClipRect.Max.y)
@@ -55732,7 +55744,7 @@ local ButtonEx_text_min, ButtonEx_text_max = ImVec2(), ImVec2()
 
 @native
 function ImGui.ButtonEx(label, size_arg, flags)
-    if size_arg == nil then size_arg = ImVec2(0, 0) end
+    if size_arg == nil then size_arg = LAYOUT_ZERO_SIZE end -- [Luau] shared read-only: CalcItemSize() only reads it
     if flags    == nil then flags    = 0            end
 
     local window = ImGui.GetCurrentWindow()
@@ -55823,7 +55835,7 @@ function ImGui.InvisibleButton(str_id, size_arg, flags)
     end
 
     -- Ensure zero-size fits to contents
-    local size = ImGui.CalcItemSize(ImVec2(size_arg.x ~= 0.0 and size_arg.x or -1.1754943508223e-38 --[[FLT_MIN]], size_arg.y ~= 0.0 and size_arg.y or -1.1754943508223e-38 --[[FLT_MIN]]), 0.0, 0.0)
+    local size = ImVec2(ImGui._CalcItemSizeXY(size_arg.x ~= 0.0 and size_arg.x or -1.1754943508223e-38 --[[FLT_MIN]], size_arg.y ~= 0.0 and size_arg.y or -1.1754943508223e-38 --[[FLT_MIN]], 0.0, 0.0))
 
     local id = window:GetID(str_id)
     local bb = ImRect(window.DC.CursorPos, window.DC.CursorPos + size)
@@ -56686,7 +56698,6 @@ end
 -- - Separator()
 -------------------------------------------------------------------------------
 
-local LAYOUT_ZERO_SIZE = ImVec2(0, 0) -- [Luau] shared read-only: ItemSize() only reads it
 local LayoutHelpers_size = ImVec2()   -- [Luau] scratch for ItemSize() arguments
 
 function ImGui.Spacing()