Fix get_plot_mouse_pos() precision by calculating on-demand

[Entrpi]

Description:

Fixes #1847 - get_plot_mouse_pos() returns imprecise/stale values when using time-scale axes with Unix timestamps.

The existing implementation caches mouse position as float during rendering, only updating when ImPlot::IsPlotHovered() returns true. This causes two problems:

1. Precision loss: float cannot represent Unix timestamps with sub-second precision
2. Stale values: The cached value doesn't update reliably, causing the position to appear "frozen"

This fix:

• Stores plot geometry (position, size, axis limits as double) during render instead of mouse position
• Adds optional plot parameter to get_plot_mouse_pos(plot=tag)
• When plot is specified, calculates position on-demand using current mouse coords + cached geometry
• Returns double precision values via FloatList instead of IntList
• Maintains full backward compatibility: no plot arg = legacy cached behavior

API change:

# New (accurate, on-demand calculation):
dpg.get_plot_mouse_pos(plot="my_plot")

# Old (still works, legacy cached value):
dpg.get_plot_mouse_pos()

Real-world use case:

This fix was developed for MPM-1010B Power Monitor, a real-time AC power monitoring tool with multi-timescale visualization. The app displays hover tooltips showing exact readings at the cursor position. Before this fix, tooltips would only update at ~7 discrete "slices" across the plot width due to float precision loss with Unix timestamps.

Concerning Areas:

• The geometry cache adds 48 bytes per plot (6 doubles)
• Calculation happens on every call when plot is specified (simple linear interpolation, negligible cost)
• Tested on macOS with Python 3.14

[v-ein]

This PR seems to also update Dear ImGui - is that correct? Unfortunately that's a no-go because we want to single out such large changes as separate PRs (see for example #2275, it was a lot of work to get everything in order).

FWIW, I'm currently working on an update of ImGui, ImPlot, and ImNodes (honestly, the latter two almost didn't change). This will be a separate PR and most probably a separate release.

Here's the plan:

• We already have a number of PRs merged into master since the last release, some of them quite large, which warrants a new release.
• We'll merge several more PRs that I need before going forward with my ImGui update.
• Once these are ready, we'll cut a release, probably version 2.2.
• Shortly after that, I'll make another PR that updates ImGui. Once this one is sufficiently tested, we'll cut yet another release, 2.3. This will hopefully be a very short release cycle, and the only reason for doing it like that is to make sure nothing "breaks too much" - and if it does, people out there have a version to roll back to.
• After 2.3, other PRs will be considered, including yours and some other quite deep-going things.

[Entrpi]

Thanks for the context on the release plan!

In case it's helpful for your upcoming ImGui update work, I've been working on porting DearPyGui to current imgui master (merged into docking). The main API changes I encountered:

ImGui 1.92+ breaking changes:

• ImGuiChildFlags_Border → ImGuiChildFlags_Borders
• ImGuiWindowFlags_NavFlattened → ImGuiChildFlags_NavFlattened
• ImFont::FontSize → LegacySize, glyph access via GetFontBaked()
• ImFontAtlas::TexID/TexWidth/TexHeight → TexRef.GetTexID(), TexData->Width/Height
• ImDrawCmd::TextureId → TexRef, ImDrawList::_TextureIdStack → _TextureStack
• ImGuiWindow::CalcFontSize() → FontRefSize
• SetCurrentFont(font) → SetCurrentFont(font, size, size)
• Metal backend: ImGui_ImplMetal_CreateFontsTexture/DestroyFontsTexture removed (now automatic)

Forks with working builds:

• imgui docking + SliderRange2: https://github.com/Entrpi/imgui/tree/docking
• DearPyGui with all API migrations: https://github.com/Entrpi/DearPyGui
• implot compatibility fixes: https://github.com/Entrpi/implot/tree/imgui-1.92-compat

Wheels building successfully for Python 3.10-3.14 on Windows x64, Linux x64/arm64, macOS arm64. Tested the new SliderRange2/DragRange2 functionality in DearPyGui with all the current edits - working as expected (drag handles, Cmd/Ctrl+Click text input, step snapping, etc.).

Also worth noting: the SliderFloatRange2/SliderIntRange2 widgets are being reviewed upstream at ocornut/imgui#9164 - Omar is actively refining the API. If it gets merged before your ImGui update, you'd get the widgets included automatically.

Happy to split out just the DearPyGui bindings for SliderRange2/DragRange2 into a separate PR once you're ready for it after 2.3.