Might be intentional, didn't find anything in issues search right now for PushStyleVar

I could understand why some might be kept "private" for sandboxing purposes (window padding, safe area, touch padding), but some of them seem like they are mostly stylistic.

Here's a list of variables that are in the ImGuiStyle struct, but not in the ImGuiStyleVar_ enum:

ImVec2 WindowTitleAlign;
ImVec2 TouchExtraPadding;
float ColumnsMinSpacing;
float ScrollbarSize;
float ScrollbarRounding;
float GrabRounding;
ImVec2 DisplayWindowPadding;
ImVec2 DisplaySafeAreaPadding;
bool AntiAliasedLines;
bool AntiAliasedShapes;
float CurveTessellationTol;