Overlapped item gets click - even with SetItemAllowOverlap

[abau]

Version/Branch of Dear ImGui:

Version: 1.89.7 WIP
Branch: master

Back-end/Renderer/Compiler/OS

Back-ends: imgui_impl_opengl2.cpp + imgui_impl_sdl2.cpp
Compiler: gcc 13.1.1
Operating System: Linux

My Issue/Question:

I tried the example given in #3909 (comment) with SetItemAllowOverlap after button 1, but unlike stated in the comment, when clicking into the intersection of both buttons, button 1 registers the click - not button 2. Did I miss anything?

[ocornut]

I believe my example in the linked comment is incorrect.

Low-level ImGuiButtonFlags_AllowItemOverlap needs to be set on the potentially overlapped item:

ImGui::ButtonEx("11111", ImVec2(50, 50), ImGuiButtonFlags_AllowItemOverlap)

As designed, I believe SetItemAllowOverlap() API is a little useless.

I believe this needs to be redesigned into, e.g. at minimum a SetNextItemAllowOverlap() variant.

[ocornut]

I believe my example in the linked comment is incorrect.

Sorry it was too hasty to me to say that when it's not that simple.

Prior to 1.89 the code in #3909 (comment) + all descriptions of behavior were fully accurate.

In 1.89 we internally started using a system for input-ownership (which wasn't really publicly advertised as a whole, but part of it was used in answers to specific problem). The way this system work broke the behavior of said snippet.
I am investigating and will post more details soon.

[abau]

ImGuiButtonFlags_AllowItemOverlap works. Thanks.

I believe this needs to be redesigned

From my point-of-view as a new Imgui-user, I expected that - by default - all subsequent widgets would take precedence when it comes to handling events. And in case this is not what the user wants, some kind of ImGuiButtonFlags_Passthrough flag could be set for subsequent widgets.

Anyways, thanks for your help.

[ocornut]

Following the recent discovery that an underlying major change in 1.89 broke use of SetItemAllowOverlap() I have worked on this topic. The resulting changes being:

Changelog:

• Added SetNextItemAllowOverlap() (called before an item) as a replacement for using SetItemAllowOverlap() (called after an item). This is roughly equivalent to using the legacy SetItemAllowOverlap() call (public API) + ImGuiButtonFlags_AllowOverlap (internal).
• Obsoleted SetItemAllowOverlap(): it didn't and couldn't work reliably since 1.89 (2022-11-15), and relied on ambiguously defined design. Use SetNextItemAllowOverlap() before item instead.
• Renamed ImGuiTreeNodeFlags_AllowItemOverlap to ImGuiTreeNodeFlags_AllowOverlap.
• Renamed ImGuiSelectableFlags_AllowItemOverlap to ImGuiSelectableFlags_AllowOverlap
• IsItemHovered: Changed behavior to return false when querying an item using AllowOverlap mode which is being overlapped. Added ImGuiHoveredFlags_AllowWhenOverlappedByItem.
• Selectable, TreeNode: When using ImGuiSelectableFlags_AllowOverlap/ImGuiTreeNodeFlags_AllowOverlap and holding item held, overlapping widgets won't appear as hovered.
• Most item types should now work with SetNextItemAllowOverlap() (previously only a fraction of widgets did).
• Fixed first frame of an overlap highlighting underlying item if previous frame didn't hover anything.
• Kept redirecting enums (will obsolete).
• IsItemHovered: Added ImGuiHoveredFlags_AllowWhenOverlappedByWindow to ignore window-overlap only. Option ImGuiHoveredFlags_AllowWhenOverlapped now expand into a combination of both ImGuiHoveredFlags_AllowWhenOverlappedByWindow + ImGuiHoveredFlags_AllowWhenOverlappedByItem, matching old behavior.

Commits

• 06f5b46 Overlap: Fixed first frame of an overlap highlighting underlying item if previous frame didn't hover anything.
• 51f564e (Breaking) Overlap: Renamed 'ImGuiTreeNodeFlags_AllowItemOverlap' to 'ImGuiTreeNodeFlags_AllowOverlap', 'ImGuiSelectableFlags_AllowItemOverlap' to 'ImGuiSelectableFlags_AllowOverlap'. Kept redirecting enums (will obsolete).
• 07e24b4 ButtonBehavior: pull ImGuiButtonFlags_Repeat from ImGuiItemFlags_ButtonRepeat, matching ItemHoverable() logic. So more widgets can take advantage of Repeat logic.
• a9a5cbf Overlap: Internals: add NextItemData.ItemFlags to facilitate implementation of SetNextItemAllowOverlap() + potentially remove extra_flags from ItemAdd().
• 8439a73 Overlap: Added 'SetNextItemAllowOverlap()' as a replacement for 'SetItemAllowOverlap()'.
• 10c7709 IsItemHovered: Changed behavior to return false when querying an item using AllowOverlap mode. Added ImGuiHoveredFlags_AllowWhenOverlappedByItem, ImGuiHoveredFlags_AllowWhenOverlappedByWindow.
• 4dee919 (Breaking) Internals: added ImGuiItemFlags param to ItemHoverable(), so it can be called from ButtonBehavior() not following an ItemAdd().
• 6137443 Overlap: moved ImGuiItemflags_AllowOverlap handling from ButtoBehavior() to ItemHoverable() now that it is possible. This allows DragXXX, SliderXXX, PlotXXX etc to honor SetNextItemAllowOverlap().

I have also updated ImPlot accordingly: epezent/implot#486