Frame hover glitch when moving on overlapping item border, with SetNextItemAllowOverlap

[wolfgang371]

Version/Branch of Dear ImGui:

1.89.9 master

Back-ends:

crsfml, 2.5.3

Compiler, OS:

gcc/crystal, Ubuntu

Full config/build information:

No response

Details:

Below code produces something like this...

when moving down (bad):

220, hover top button
221, hover top button, hover bottom button
222, hover bottom button

when moving up (bad):

252, hover bottom button
253
254, hover top button

Screenshots/Video:

No response

Minimal, Complete and Verifiable Example code:

ImGui.set_next_item_allow_overlap # important
pos = ImGui.get_cursor_pos
ImGui.button("##button3", ImVec2.new(50.0,50.0))
h1 = ImGui.is_item_hovered
pos.y += 25
ImGui.set_cursor_pos(pos)
ImGui.button("##button4", ImVec2.new(50.0,50.0)) # button or dummy, irrelevant
# ImGui.dummy(ImVec2.new(50.0,50.0)) # button or dummy, irrelevant
h2 = ImGui.is_item_hovered
puts [ImGui.get_frame_count, h1 ? "hover top button" : nil, h2 ? "hover bottom button" : nil].reject(&.nil?).join(", ")

[ocornut]

Here's the C++ repro:

// #7515
{
    ImGui::SeparatorText("#7515");
    ImVec2 pos = ImGui::GetCursorPos();

    ImGui::SetNextItemAllowOverlap();
    ImGui::Button("button3", { 50.0f, 50.0f });
    bool h1 = ImGui::IsItemHovered();
    pos.y += 25;
    ImGui::SetCursorPos(pos);
    ImGui::Button("Button4", { 50.0f, 50.0f });// # button or dummy, irrelevant
    //ImGui::Dummy({ 50.0f, 50.0f });
    bool h2 = ImGui::IsItemHovered();
    if (h1 || h2)
        printf("[%05d] %s%s\n", ImGui::GetFrameCount(), h1 ? "hover top button" : "", h2 ? "hover bottom button" : "");
}

when moving down (bad):
220, hover top button
221, hover top button, hover bottom button
222, hover bottom button

I consider this an issue, let me investigate.

when moving up (bad):
252, hover bottom button
253
254, hover top button

This is the same as #7514 and I don't consider this an issue.

[ocornut]

I have a pushed a test for the current behavior (which isn't necessarily correct)
ocornut/imgui_test_engine@33b9786
In particular I think the third section showcase the difference between IsItemHovered() and hover state as reported via ButtonBehavior()->ItemHoverable().

So if we introduce changes we can aim to validate them against current test and fix the test accordingly.