size_t CurTabOpen = 0;

void AddTab(size_t Index, const char* Text)
{
	static const size_t TabWidth			= 85;
	static const size_t TabHeight			= 18;

	ImGui::PushID(Index);
	ImGui::PushStyleVar(ImGuiStyleVar_FrameBorderSize, 1);

	if (Index == 1)
		ImGui::SameLine(Index * (TabWidth + 5));
	else if (Index > 1)
		ImGui::SameLine(Index * (TabWidth + 4 - Index));

	if (CurTabOpen == Index)
		ImGui::PushStyleColor(ImGuiCol_Button, (ImVec4)ImColor(15, 15, 15));			// Color on tab open
	else
		ImGui::PushStyleColor(ImGuiCol_Button, (ImVec4)ImColor(30, 30, 30));			// Color on tab closed

	ImGui::PushStyleColor(ImGuiCol_ButtonHovered, (ImVec4)ImColor(40, 40, 40));			// Color on mouse hover in tab
	ImGui::PushStyleColor(ImGuiCol_ButtonActive, (ImVec4)ImColor(35, 35, 35));			// Color on click tab

	if (ImGui::Button(Text, ImVec2(TabWidth, TabHeight)))	// If tab clicked
		CurTabOpen = Index;

	ImGui::PopStyleVar();
	ImGui::PopStyleColor(3);
	ImGui::PopID();
}

Example:
AddTab(0, "Aimbot");
AddTab(1, "Triggerbot");
AddTab(2, "Visual");
AddTab(3, "Weapon");
AddTab(4, "Player");
AddTab(5, "Config");

switch (CurTabOpen)
{
	case 0:
		// Aimbot tab draws here
	break;
	case 1:
		// Triggerbot tab draws here
	break;
	case 2:
		// Visual tab draws here
	break;
	case 3:
		// Weapon tab draws here
	break;
	case 4:
		// Player tab draws here
	break;
	case 5:
		// Config tab draws here
	break;
}