Nesting a Begin() inside a BeginTable() reports wrong GetContentRegionAvail().y

[Intrets]

Version/Branch of Dear ImGui:

Version 1.92, Branch: master

Back-ends:

imgui_impl_glfw.cpp + imgui_impl_opengl.cpp

Compiler, OS:

Fedora 42 + clang

Full config/build information:

No response

Details:

Attached video shows the problem, attached code produces the two windows shown in the video.

In the attached code, contents in the function contents I want to display in a regular window, and in a window inside a table. In my original code where I came across this issue the problem showed up as the child window taking up all (wrongly) available space instead of showing a scrollbar, I have left this out of the MVCE, and instead show the problem by looking at GetContentRegionAvail().y.

Displaying contents does not do what I expect in the case where the Begin and contents gets called inside a table.

In the video pay attention to the second GetContentRegionAvail().y.

At the start I show the broken setup, with all the checkboxes enabled for all the needed components for the wrong values to show up. After that I go through all the combinations and even just disabling one part fixes it.

Am I doing something that is not allowed? I expect the contents to work exactly the same in both setups.

Screenshots/Video:

out.mp4

Minimal, Complete and Verifiable Example code:

void contents() {
	ImGui::Text("GetContentRegionAvail().x: %f", ImGui::GetContentRegionAvail().x);
	ImGui::Text("GetContentRegionAvail().y: %f", ImGui::GetContentRegionAvail().y);

	static bool table = true;
	ImGui::Checkbox("Table", &table);

	if (table) {
		if (ImGui::BeginTable("Table", 1)) {
			ImGui::TableNextColumn();
			ImGui::Text("Table Contents");
		}
		ImGui::EndTable();
	}

	ImGui::Text("GetContentRegionAvail().x: %f", ImGui::GetContentRegionAvail().x);
	ImGui::Text("GetContentRegionAvail().y: %f", ImGui::GetContentRegionAvail().y);

	static bool child = true;
	ImGui::Checkbox("Child", &child);

	if (child) {
		ImGui::BeginChild("Child Window");
		ImGui::Text("Child Contents");
		ImGui::EndChild();
	}
}

void contentsInWindow() {
	if (ImGui::Begin("Window")) {
		contents();
	}
	ImGui::End();
}

// execute this in ImGui loop
void runBroken() {
	static bool modalTable = true;
	ImGui::Checkbox("contensInWindow() inside a table", &modalTable);

	if (modalTable) {
		if (ImGui::BeginTable("Begin Table", 1)) {
			ImGui::TableNextColumn();

			contentsInWindow();

			ImGui::EndTable();
		}
	}
	else {
        contentsInWindow();
	}
}

[Intrets]

Ok I realised this has not actually anything to do with PopupModal I will edit the issue, instead it is an issue with the specific setup of, table -> window -> table -> look at height -> child issue updated

[ocornut]

Thank you for the report and useful repro.

I'm currently investigating but I can easily state this is a bug because contentsInWindow() calls ImGui::Begin("Window") and this window in theory should not "inherit" any property from whatever is already in the stack, so the mere fact that this creates a side-effect is itself a bug to investigate.

[ocornut]

This should be fixed with d7fec5e.

[Intrets]

Confirmed it also fixed the issue in my original code thanks for the very quick fix.