LVCOLUMN lvCol;
lvCol.mask = LVCF_TEXT | LVCF_WIDTH;
lvCol.pszText = L"Column Header Text";
m_pBtnList->InsertColumn(0, &lvCol);
You specify here that the
cx
(width) field is valid, but you have not set its value. So it will be whatever value happens to exist in that cell on the stack.