Issue numbers (#) refer to github issues listed at https://github.com/ocornut/imgui/issues/XXXX
The list below consist mostly of ideas noted down before they are requested/discussed by users (at which point they usually exist on the github issue tracker).
It's mostly a bunch of personal notes, probably incomplete. Feel free to query if you have any questions.
- doc/test: add a proper documentation+regression testing system (#435)
- doc/test: checklist app to verify binding/integration of imgui (test inputs, rendering, callback, etc.).
- doc/tips: tips of the day: website? applet in imgui_club?
- window: calling SetNextWindowSize() every frame with <= 0 doesn't do anything, may be useful to allow (particularly when used for a single axis). (#690)
- window: add a way for very transient windows (non-saved, temporary overlay over hundreds of objects) to "clean" up from the global window list. perhaps a lightweight explicit cleanup pass.
- window: auto-fit feedback loop when user relies on any dynamic layout (window width multiplier, column) appears weird to end-user. clarify.
- window: allow resizing of child windows (possibly given min/max for each axis?.)
- window: using SetWindowPos() inside Begin() and moving the window with the mouse reacts a very ugly glitch. We should just defer the SetWindowPos() call.
- window/opt: freeze window flag: if not focused/hovered, return false, render with previous ImDrawList. and/or reduce refresh rate. -> this may require enforcing that it is illegal to submit contents if Begin returns false.
- window/child: the first draw command of a child window could be moved into the current draw command of the parent window (unless child+tooltip?).
- window/child: border could be emitted in parent as well.
- window/child: allow SetNextWindowContentSize() to work on child windows.
- window/clipping: some form of clipping when DisplaySize (or corresponding viewport) is zero.
- window/tab: add a way to signify that a window or docked window requires attention (e.g. blinking title bar).
! scrolling: exposing horizontal scrolling with Shift+Wheel even when scrollbar is disabled expose lots of issues (#2424, #1463)
- scrolling: while holding down a scrollbar, try to keep the same contents visible (at least while not moving mouse)
- drawlist: end-user probably can't call Clear() directly because we expect a texture to be pushed in the stack.
- drawlist: maintaining bounding box per command would allow to merge draw command when clipping isn't relied on (typical non-scrolling window or non-overflowing column would merge with previous command).
- drawlist: primitives/helpers to manipulate vertices post submission, so e.g. a quad/rect can be resized to fit later submitted content, _without_ using the ChannelSplit api
- drawlist: would be good to be able to deep copy of ImDrawData (we have a deep copy of ImDrawList now).
- drawlist: rendering: provide a way for imgui to output to a single/global vertex buffer, re-order indices only at the end of the frame (ref: https://gist.github.com/floooh/10388a0afbe08fce9e617d8aefa7d302)
- drawlist: callback: add an extra void* in ImDrawCallback to allow passing render-local data to the callback (would break API).
- main: find a way to preserve relative orders of multiple reappearing windows (so an app toggling between "modes" e.g. fullscreen vs all tools) won't lose relative ordering.
- main: IsItemHovered() make it more consistent for various type of widgets, widgets with multiple components, etc. also effectively IsHovered() region sometimes differs from hot region, e.g tree nodes
- main: IsItemHovered() info stored in a stack? so that 'if TreeNode() { Text; TreePop; } if IsHovered' return the hover state of the TreeNode?
- main: rename the main "Debug" window to avoid ID collision with user who may want to use "Debug" with specific flags.
- widgets: display mode: widget-label, label-widget (aligned on column or using fixed size), label-newline-tab-widget etc. (#395)
- widgets: clean up widgets internal toward exposing everything and stabilizing imgui_internals.h.
- widgets: add always-allow-overlap mode. This should perhaps be the default? one problem is that highlight after mouse-wheel scrolling gets deferred, makes scrolling more flickery.
- widgets: a way to represent "mixed" values, so e.g. all values replaced with *, including check-boxes, colors, etc. with support for multi-components widgets (e.g. SliderFloat3, make only "Y" mixed) (#2644)
- widgets: selectable: a way to visualize partial/mixed selection (e.g. parent tree node has children with mixed selection)
- widgets: checkbox: checkbox with custom glyph inside frame.
- widgets: coloredit: keep reporting as active when picker is on?
- widgets: group/scalarn functions: expose more per-component information. e.g. store NextItemData.ComponentIdx set by scalarn function, groups can expose them back somehow.
- input text: easier ways to update buffer (from source char*) while owned. preserve some sort of cursor position for multi-line text.
- input text: add discard flag (e.g. ImGuiInputTextFlags_DiscardActiveBuffer) or make it easier to clear active focus for text replacement during edition (#725)
- input text: display bug when clicking a drag/slider after an input text in a different window has all-selected text (order dependent). actually a very old bug but no one appears to have noticed it.
- input text: allow centering/positioning text so that ctrl+clicking Drag or Slider keeps the textual value at the same pixel position.
- input text multi-line: don't directly call AddText() which does an unnecessary vertex reserve for character count prior to clipping. and/or more line-based clipping to AddText(). and/or reorganize TextUnformatted/RenderText for more efficiency for large text (e.g TextUnformatted could clip and log separately, etc).
- input text multi-line: support for cut/paste without selection (cut/paste the current line)
- input text multi-line: line numbers? status bar? (follow up on #200)
- input text multi-line: behave better when user changes input buffer while editing is active (even though it is illegal behavior). namely, the change of buffer can create a scrollbar glitch (#725)
- input text multi-line: better horizontal scrolling support (#383, #1224)
- input number: optional range min/max for Input*() functions
- input number: holding [-]/[+] buttons could increase the step speed non-linearly (or user-controlled)
- input number: use mouse wheel to step up/down
- input number: applying arithmetics ops (+,-,*,/) messes up with text edit undo stack.
- layout: helper or a way to express ImGui::SameLine(ImGui::GetCursorStartPos().x + ImGui::CalcItemWidth() + ImGui::GetStyle().ItemInnerSpacing.x); in a simpler manner.
- layout: generalization of the above: a concept equivalent to word processor ruler tab stop ~ mini columns (position in X, no clipping implied) (vaguely relate to #267, #395, also what is used internally for menu items)
- layout: horizontal layout helper (#97)
- layout: horizontal flow until no space left (#404)
- layout: more generic alignment state (left/right/centered) for single items?
- layout: clean up the InputFloatN/SliderFloatN/ColorEdit4 layout code. item width should include frame padding.
- layout: null layout mode were items are not rendered but user can query GetItemRectMin()/Max/Size.
- layout: (R&D) local multi-pass layout mode.
- layout: (R&D) bind authored layout data (created by an off-line tool), items fetch their pos/size at submission, self-optimize data structures to stable linear access.
- group: BeginGroup() needs a border option. (~#1496)
- group: IsHovered() after EndGroup() covers whole aabb rather than the intersection of individual items. Is that desirable?
- group: merge deactivation/activation within same group (fwd WasEdited flag). (#2550)
- plot: add a helper e.g. Plot(char* label, float value, float time_span=2.0f) that stores values and Plot them for you - probably another function name. and/or automatically allow to plot ANY displayed value (more reliance on stable ID)
- clipper: ability to force display 1 item in the list would be convenient (for patterns where we need to set active id etc.)
- clipper: ability to disable the clipping through a simple flag/bool.
- clipper: ability to run without knowing full count in advance.
- image/image button: misalignment on padded/bordered button?
- image/image button: parameters are confusing, image() has tint_col,border_col whereas imagebutton() has bg_col/tint_col. Even thou they are different parameters ordering could be more consistent. can we fix that?
- drag float: added leeway on edge (e.g. a few invisible steps past the clamp limits)
- combo: use clipper: make it easier to disable clipper with a single flag.
- combo: flag for BeginCombo to not return true when unchanged (#1182)
- combo: a way/helper to customize the combo preview (#1658)
- combo/listbox: keyboard control. need InputText-like non-active focus + key handling. considering keyboard for custom listbox (pr #203)
- listbox: refactor and clean the begin/end api
- listbox: multiple selection.
- listbox: unselect option (#1208)
- listbox: make it easier/more natural to implement range-select (need some sort of info/ref about the last clicked/focused item that user can translate to an index?) (wip stash)
- listbox: user may want to initial scroll to focus on the one selected value?
- listbox: expose hovered item for a basic ListBox
!- popups/menus: clarify usage of popups id, how MenuItem/Selectable closing parent popups affects the ID, etc. this is quite fishy needs improvement! (#331, #402)
- popups: reopening context menu at new position should be the behavior by default? (equivalent to internal OpenPopupEx() with reopen_existing=true) (~#1497)
- popups: if the popup functions took explicit ImGuiID it would allow the user to manage the scope of those ID. (#331)
- popups: clicking outside (to close popup) and holding shouldn't drag window below.
- popups: add variant using global identifier similar to Begin/End (#402)
- popups: border options. richer api like BeginChild() perhaps? (#197)
- tooltip: drag and drop with tooltip near monitor edges lose/changes its last direction instead of locking one. The drag and drop tooltip should always follow without changing direction.
- tooltip: tooltips with delay timers? or general timer policy? (instantaneous vs timed): IsItemHovered() with timer + implicit aabb-id for items with no ID. (#1485)
- text: selectable text (for copy) as a generic feature (ItemFlags?)
- text: proper alignment options in imgui_internal.h
- text: it's currently impossible to have a window title with "##". perhaps an official workaround would be nice. \ style inhibitor? non-visible ascii code to insert between #?
- text: provided a framed text helper, e.g. https://pastebin.com/1Laxy8bT
- settings/persistence: helpers to make TreeNodeBehavior persist (even during dev!) - may need to store some semantic and/or data type in ImGuiStoragePair
- style: add a highlighted text color (for headers, etc.)
- style: border types: out-screen, in-screen, etc. (#447)
- style: add window shadow (fading away from the window. Paint-style calculation of vertices alpha after drawlist would be easier)
- style: a concept of "compact style" that the end-user can easily rely on (e.g. PushStyleCompact()?) that maps to other settings? avoid implementing duplicate helpers such as SmallCheckbox(), etc.
- style: try to make PushStyleVar() more robust to incorrect parameters (to be more friendly to edit & continues situation).
- style: WindowPadding needs to be EVEN as the 0.5 multiplier used on this value probably have a subtle effect on clip rectangle
- style: have a more global HSV setter (e.g. alter hue on all elements). consider replacing active/hovered by offset in HSV space? (#438, #707, #1223)
- style: gradients fill (#1223) ~ 2 bg colors for each fill? tricky with rounded shapes and using textures for corners.
- style editor: color child window height expressed in multiple of line height.
- log: have more control over the log scope (e.g. stop logging when leaving current tree node scope)
- log: be able to log anything (e.g. right-click on a window/tree-node, shows context menu? log into tty/file/clipboard)
- log: let user copy any window content to clipboard easily (CTRL+C on windows? while moving it? context menu?). code is commented because it fails with multiple Begin/End pairs.
- drag and drop: drag tooltip hovering over source widget with IsItemHovered/SetTooltip flickers.
- drag and drop: fix/support/options for overlapping drag sources.
- drag and drop: releasing a drop shows the "..." tooltip for one frame - since e13e598 (#1725)
- drag and drop: drag source on a group object (would need e.g. an invisible button covering group in EndGroup) https://twitter.com/paniq/status/1121446364909535233
- drag and drop: have some way to know when a drag begin from BeginDragDropSource() pov. (see 2018/01/11 post in #143)
- drag and drop: make it easier and provide a demo to have tooltip both are source and target site, with a more detailed one on target site (tooltip ordering problem)
- drag and drop: allow for multiple payload types. (#143)
- drag and drop: make payload optional? payload promise? (see 2018/01/11 post in #143)
- drag and drop: (#143) "both an in-process pointer and a promise to generate a serialized version, for whether the drag ends inside or outside the same process"
- drag and drop: feedback when hovering a region blocked by modal (mouse cursor "NO"?)
- font: a CalcTextHeight() helper could run faster than CalcTextSize().y
- font: enforce monospace through ImFontConfig (for icons?) + create dual ImFont output from same input, reusing rasterized data but with different glyphs/AdvanceX
- font: storing MinAdvanceX per font would allow us to skip calculating line width (under a threshold of character count) in loops looking for block width
- font/demo: add tools to show glyphs used by a text blob, display U16 value, list missing glyphs.
- font/demo: demonstrate use of ImFontGlyphRangesBuilder.
- font/draw: underline, squiggle line rendering helpers.
- font: optimization: for monospace font (like the default one) we can trim IndexXAdvance as long as trailing value is == FallbackXAdvance (need to make sure TAB is still correct), would save on cache line.
- font: add support for kerning, probably optional. A) perhaps default to (32..128)^2 matrix ~ 9K entries = 36KB, then hash for non-ascii?. B) or sparse lookup into per-char list?
- font: add a simpler CalcTextSizeA() api? current one ok but not welcome if user needs to call it directly (without going through ImGui::CalcTextSize)
- font: fix AddRemapChar() to work before atlas has been built.
- font: what would it take to support codepoint higher than 0xFFFF? (smileys, etc.) (#2538, #2541)
- font: (api breaking) remove "TTF" from symbol names. also because it now supports OTF.
- font/opt: Considering storing standalone AdvanceX table as 16-bit fixed point integer?
- font/opt: Glyph currently 40 bytes (2+9*4). Consider storing UV as 16 bits integer? (->32 bytes). X0/Y0/X1/Y1 as 16 fixed-point integers? Or X0/Y0 as float and X1/Y1 as fixed8_8?
- nav: wrap around logic to allow e.g. grid based layout (pressing NavRight on the right-most element would go to the next row, etc.). see internal's NavMoveRequestTryWrapping().
- nav: patterns to make it possible for arrows key to update selection
- nav: restore/find nearest NavId when current one disappear (e.g. pressed a button that disappear, or perhaps auto restoring when current button change name)
- nav: SetItemDefaultFocus() level of priority, so widget like Selectable when inside a popup could claim a low-priority default focus on the first selected iem
- nav: ESC within a menu of a child window seems to exit the child window.
- nav: NavFlattened: ESC on a flattened child should select something.
- nav: NavFlattened: broken: in typical usage scenario, the items of a fully clipped child are currently not considered to enter into a NavFlattened child.
- nav: NavFlattened: init request doesn't select items that are part of a NavFlattened child
- nav: NavFlattened: cannot access menu-bar of a flattened child window with Alt/menu key (not a very common use case..).
- nav/menus: pressing left-right on a vertically clipped menu bar tends to jump to the collapse/close buttons.
- nav/menus: allow pressing Menu to leave a sub-menu.
- nav/menus: a way to access the main menu bar with Alt? (currently needs CTRL+TAB)
- nav/menus: when using the main menu bar, even though we restore focus after, the underlying window loses its title bar highlight during menu manipulation. could we prevent it?
- nav/menus: main menu bar currently cannot restore a NULL focus. Could save NavWindow at the time of being focused, similarly to what popup do?
- nav: simulate right-click or context activation? (SHIFT+F10)
- nav: tabs should go through most/all widgets (in submission order?).
- nav: when CTRL-Tab/windowing is active, the HoveredWindow detection doesn't take account of the window display re-ordering.
- nav: esc/enter default behavior for popups, e.g. be able to mark an "ok" or "cancel" button that would get triggered by those keys.
- nav: when activating a button that changes label (without a static ID) or disappear, can we somehow automatically recover into a nearest highlight item?
- nav: there's currently no way to completely clear focus with the keyboard. depending on patterns used by the application to dispatch inputs, it may be desirable.
- focus: preserve ActiveId/focus stack state, e.g. when opening a menu and close it, previously selected InputText() focus gets restored (#622)
- focus: SetKeyboardFocusHere() on with >= 0 offset could be done on same frame (else latch and modulate on beginning of next frame)
- focus: unable to use SetKeyboardFocusHere() on clipped widgets. (#787)
- inputs: we need an explicit flag about whether the imgui window is focused, to be able to distinguish focused key releases vs alt-tabbing all release behaviors.
- inputs: rework IO system to be able to pass actual ordered/timestamped events. use an event queue? (~#335, #71)
- inputs: support track pad style scrolling & slider edit.
- misc: idle: expose "woken up" boolean (set by inputs) and/or animation time (for cursor blink) for back-end to be able stop refreshing easily.
- misc: idle: if cursor blink if the _only_ visible animation, core imgui could rewrite vertex alpha to avoid CPU pass on ImGui:: calls.
- misc: idle: if cursor blink if the _only_ visible animation, could even expose a dirty rectangle that optionally can be leverage by some app to render in a smaller viewport, getting rid of much pixel shading cost.
- emscriptem: with refactored examples, we could provide a direct imgui_impl_emscripten platform layer (see eg. https://github.com/floooh/sokol-samples/blob/master/html5/imgui-emsc.cc#L42)
- examples: provide a zero frame-rate/idle example.
- examples: apple: example_apple should be using modern GL3.
- examples: glfw: could go idle when minimized? if (glfwGetWindowAttrib(window, GLFW_ICONIFIED)) { glfwWaitEvents(); continue; } // issue: DeltaTime will be super high on resume, perhaps provide a way to let impl know (#440)
- optimization: replace vsnprintf with stb_printf? or enable the defines/infrastructure to allow it (#1038)
- optimization: add clipping for multi-component widgets (SliderFloatX, ColorEditX, etc.). one problem is that nav branch can't easily clip parent group when there is a move request.
- optimization: add a flag to disable most of rendering, for the case where the user expect to skip it (#335)
- optimization: use another hash function than crc32, e.g. FNV1a
- optimization/render: merge command-lists with same clip-rect into one even if they aren't sequential? (as long as in-between clip rectangle don't overlap)?
- optimization: turn some the various stack vectors into statically-sized arrays