Combo jitters inside Table when _SizingStretchProp is set about imgui

[ocornut]

You have a feedback loop using “ imgui::SetNextItemWidth(ImGui::GetContentRegionAvail().x);” which uses the column width for the framed part of the combo, and the column itself measuring its contents to set its width proportional to contents to both columns. Unfortunately one of those parameters would need to be altered.

[rayment]

Hi Omar, thanks for getting back to me. What you say makes perfect sense, though unfortunately this issue occurs even without the second row with SetNextItemWidth.

ImGui::Begin("window");
	ImGui::BeginTable("table_broken", 2, ImGuiTableFlags_SizingStretchProp);
		ImGui::TableNextRow();
		ImGui::TableSetColumnIndex(0);
		ImGui::Text("broken");
		ImGui::TableSetColumnIndex(1);
		if (ImGui::BeginCombo("##combo", "this table jitters"))
			ImGui::EndCombo();
	ImGui::EndTable();
	ImGui::BeginTable("table_working", 2, ImGuiTableFlags_SizingStretchProp);
		ImGui::TableNextRow();
		ImGui::TableSetColumnIndex(0);
		ImGui::Text("working");
		ImGui::TableSetColumnIndex(1);
		ImGui::Text("but this table is fine");
	ImGui::EndTable();
ImGui::End();

This is the same code as above, just without the second row. I get the following happening:

simplescreenrecorder-2024-03-28_22.30.40.mp4

It's happening to a lesser extent, but it's particularly noticeable when the width is increased.

[rayment]

Actually it's pretty noticeable when I extend the window further:

The right extent of the Combo moves smoothly, it's entirely the left extent that is shifting every 2nd or so frame, resulting in the jittering effect.

simplescreenrecorder-2024-03-28_22.39.05.mp4

[rayment]

I can confirm it happens on Windows as well. On my 165Hz monitor it's a lot smoother but it still happens.

arc_IEa2KMBRTG.mp4