This will be part of 1.89.7 Tagged relase.

Simplified for master branch.

# Conflicts:
#	backends/imgui_impl_vulkan.cpp

Co-authored-by: Caio Oliveira <cmarcelo@gmail.com>
Simplified for master branch.

# Conflicts:
#	backends/imgui_impl_vulkan.cpp

Inputs, Tooltip: Rework stationary timer logic as it broke on high-framerates with lower rate of mouse inputs. (#1485)

InputText: ImGuiInputTextCallbackData::InsertChars() accept (NULL,NULL) range, in order to conform to common idioms.  (#6565, #6566, #3615)

Combo: Made simple/legacy Combo() function not returns true when picking already selected item. (#1182)

Overlap: moved ImGuiItemflags_AllowOverlap handling from ButtoBehavior() to ItemHoverable() now that it is possible.  (#6512, #3909, #517)

This allows DragXXX, SliderXXX, PlotXXX etc to honor SetNextItemAllowOverlap().

(Breaking) Internals: added ImGuiItemFlags param to ItemHoverable(), so it can be called from ButtonBehavior() not following an ItemAdd().

This also allow moving AllowOverlap logic from ButtonBehavior() to ItemHoverable(), allowing other widgets to honor it. (#6512, #3909, #517)

Overlap: IsItemHovered: Changed behavior to return false when querying an item using AllowOverlap mode. Added ImGuiHoveredFlags_AllowWhenOverlappedByItem, ImGuiHoveredFlags_AllowWhenOverlappedByWindow., (#6512, #3909, #517)

Overlap: Added 'SetNextItemAllowOverlap()' as a replacement for 'SetItemAllowOverlap()'. (#6512, #3909, #517)

# Conflicts:
#	imgui.cpp
#	imgui_widgets.cpp

Overlap: Internals: add NextItemData.ItemFlags to facilitate implementation of SetNextItemAllowOverlap() + potentially remove extra_flags from ItemAdd().  (#6512, #3909)

ButtonBehavior: pull ImGuiButtonFlags_Repeat from ImGuiItemFlags_ButtonRepeat, matching ItemHoverable() logic. So more widgets can take advantage of Repeat logic.

(Breaking) Overlap: Renamed 'ImGuiTreeNodeFlags_AllowItemOverlap' to 'ImGuiTreeNodeFlags_AllowOverlap', 'ImGuiSelectableFlags_AllowItemOverlap' to 'ImGuiSelectableFlags_AllowOverlap'. Kept redirecting enums (will obsolete). (#6512, #3909, #517)

+ Internals: Renamed 'ImGuiButtonFlags_AllowItemOverlap' to 'ImGuiButtonFlags_AllowOverlap' without redirection.

Overlap: Fixed first frame of an overlap highlighting underlying item if previous frame didn't hover anything. (#6512, #3909, #517)

Amend d5d4d709

Drag and Drop: moved "drag souce doesn't report as hovered" from ButtonBehavior() to ItemHoverable().

Ensure DragXXX, SliderXXXX, InputText, PlotXXX follow same logic. Amend 251f178a, a33f0d1f

Selectable, TreeNode: When using ImGuiSelectableFlags_AllowOverlap/ImGuiTreeNodeFlags_AllowOverlap and holding item held, overlapping widgets won't appear as hovered. (#6512, #3909)

Essentially we are going to remove calls to SetItemAllowOverlap() and standardize the fact that only 'HoveredId == id' test from it is performed.

# Conflicts:
#	imgui_widgets.cpp

Tables: removed misleading, seemingy useless use of ImGuiButtonFlags_AllowtemOverlap in TableUpdateBorders().  (#6512, #3909)

This was copied from SplitterBehavior(). The only hypothetical value in SplitterBehavior() would be ability to manually call SetItemAllowOverlap() after the call.
Btw generally AllowOverlap is undesirable for columns as e.g. a spanning selectable would cover entire width and prevent columns from being used.

# Conflicts:
#	imgui_tables.cpp

InputText: Fixed not returning true when buffer is cleared by ImGuiInputTextFlags_EscapeClearsAll. (#5688, #2620)

Backends: OpenGL3: Fixed erroneous use glGetIntegerv(GL_CONTEXT_PROFILE_MASK) on contexts lower than 3.2. (#6539, #6333)

TreeNode: Added support for ImGuiTreeNodeFlags_UpsideDownArrow in frameless tree nodes (#6517, #6538)

IsItemHovered, Tooltips: Added io.HoveredFlagsForTooltipMouse, io.HoveredFlagsForTooltipNav now pulled by ImGuiHoveredFlags_Tooltip. (#1485)

Update demo accordingly.

(Breaking) Moved io.HoverDelayShort/io.HoverDelayNormal to style.HoverDelayShort/style.HoverDelayNormal. (#1485)

Amend eec344cc

+ Minor tweak comment/layout in ImGuiIO

Internals: Tooltips: renamed internal flags (expecting to expose later when we publish priority stuff).