A Selectable is Selected on right clicked when ImGuiMultiSelectFlags_SelectOnClickRelease is enable

[shinji12345]

Version/Branch of Dear ImGui:

Version 1.91.6 WIP (19151), Branch: docking

Back-ends:

imgui_impl_dx12.cpp + imgui_impl_win32.cpp

Compiler, OS:

Windows11 + msvc2022

Full config/build information:

Dear ImGui 1.91.6 WIP (19151)
--------------------------------
sizeof(size_t): 8, sizeof(ImDrawIdx): 2, sizeof(ImDrawVert): 20
define: __cplusplus=199711
define: _WIN32
define: _WIN64
define: _MSC_VER=1938
define: _MSVC_LANG=201402
define: IMGUI_HAS_VIEWPORT
define: IMGUI_HAS_DOCK
--------------------------------
io.BackendPlatformName: imgui_impl_win32
io.BackendRendererName: imgui_impl_dx12
io.ConfigFlags: 0x00000483
 NavEnableKeyboard
 NavEnableGamepad
 DockingEnable
 ViewportsEnable
io.ConfigViewportsNoDecoration
io.ConfigNavCaptureKeyboard
io.ConfigInputTextCursorBlink
io.ConfigWindowsResizeFromEdges
io.ConfigMemoryCompactTimer = 60.0
io.BackendFlags: 0x00001C0E
 HasMouseCursors
 HasSetMousePos
 PlatformHasViewports
 HasMouseHoveredViewport
 RendererHasVtxOffset
 RendererHasViewports
--------------------------------
io.Fonts: 1 fonts, Flags: 0x00000000, TexSize: 512,64
io.DisplaySize: 1264.00,761.00
io.DisplayFramebufferScale: 1.00,1.00
--------------------------------
style.WindowPadding: 8.00,8.00
style.WindowBorderSize: 1.00
style.FramePadding: 4.00,3.00
style.FrameRounding: 0.00
style.FrameBorderSize: 0.00
style.ItemSpacing: 8.00,4.00
style.ItemInnerSpacing: 4.00,4.00

Details:

When ImGuiMultiSelectFlags_SelectOnClickRelease is enabled, a selectable is selected on mouse released for the left botton, but on mouse clicked for the right button.

Screenshots/Video:

Minimal, Complete and Verifiable Example code:

const int ITEMS_COUNT = 50;
static ImGuiSelectionBasicStorage selection;
static ImGuiMultiSelectFlags flags = ImGuiMultiSelectFlags_ClearOnEscape | ImGuiMultiSelectFlags_BoxSelect1d;

if (ImGui::CheckboxFlags("ImGuiMultiSelectFlags_SelectOnClickRelease", &flags, ImGuiMultiSelectFlags_SelectOnClickRelease) && (flags & ImGuiMultiSelectFlags_SelectOnClickRelease))
    flags &= ~ImGuiMultiSelectFlags_SelectOnClick;

static char* message = "";
if (ImGui::IsMouseClicked(ImGuiMouseButton_Left)) { message = "Left clicked"; }
else if (ImGui::IsMouseClicked(ImGuiMouseButton_Right)) { message = "Right clicked"; }
else if (ImGui::IsMouseReleased(ImGuiMouseButton_Left)) { message = "Left Released"; }
else if (ImGui::IsMouseReleased(ImGuiMouseButton_Right)) { message = "Right Released"; }
ImGui::Text(message);

if (ImGui::BeginChild("##Basket", ImVec2(-FLT_MIN, ImGui::GetFontSize() * 20), ImGuiChildFlags_FrameStyle | ImGuiChildFlags_ResizeY))
{
    ImGuiMultiSelectIO* ms_io = ImGui::BeginMultiSelect(flags, selection.Size, ITEMS_COUNT);
    selection.ApplyRequests(ms_io);
    for (int n = 0; n < ITEMS_COUNT; n++)
    {
        char label[64];
        bool item_is_selected = selection.Contains((ImGuiID)n);
        const char* selected = item_is_selected ? "Selected" : "Unselected";
        sprintf(label, "Object %05d: Item (%s)", n, selected);
        ImGui::SetNextItemSelectionUserData(n);
        ImGui::Selectable(label, item_is_selected);
    }
    ms_io = ImGui::EndMultiSelect();
    selection.ApplyRequests(ms_io);
}
ImGui::EndChild();

[ocornut]

That's indeed the case. I forgot why right now but it was intended and seemed desirable at the time (I'll try to check my notes and tests).
Why it is a problem for you?

[ocornut]

To clarify, that processing is automatically only enabled for Selectable in a multi-select context.
Application like Visual Studio or Windows Explorer also seems to process the right-click selection on mouse down (and menus appears on menu up).
There was another question related to similar code in #5816, but it's different from your question.