idNumeric ID identifying the child window, popup, or selection entry, passed directly without string hashing.
sizeChild-window width and height in pixels: 0 uses the remaining region, positive fixes an axis, negative uses remaining space minus that amount.
window_flagsImGuiWindowFlags options controlling this operation; combine compatible flag bits with |.
True when child contents should be submitted; false when fully clipped or collapsed. Call EndChild() even when false (EndChildFrame() for the legacy frame helper).
Begin a child window styled like a framed widget using the legacy helper.