# Cannot select first opacity control point with mouse in transfer function editor because scalar-range handle blocks this option
**URL:** https://discourse.paraview.org/t/cannot-select-first-opacity-control-point-with-mouse-in-transfer-function-editor-because-scalar-range-handle-blocks-this-option/17312
**Category:** Development
**Created:** [November 17, 2025, 4:23am UTC](https://discourse.paraview.org/t/cannot-select-first-opacity-control-point-with-mouse-in-transfer-function-editor-because-scalar-range-handle-blocks-this-option/17312 "2025-11-17T04:23:54Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@swilliams\_KMT](https://discourse.paraview.org/u/swilliams_KMT)
#### Post date: [November 17, 2025, 4:23am UTC](https://discourse.paraview.org/t/cannot-select-first-opacity-control-point-with-mouse-in-transfer-function-editor-because-scalar-range-handle-blocks-this-option/17312/1 "2025-11-17T04:23:54Z")
I see this issue has been raised a few times over the years but it still persists.
The leftmost (and rightmost) opacity control points in the transfer-function editor cannot be selected with the mouse because the scalar-range handle sits directly on top of them and takes priority for mouse selection, so clicking the point always grabs the range handle instead.
The only way to edit the endpoint value is via the table view. Unless you’re familiar with Paraview this behavior is not intuitive when all other points can be selected and manipulated.
Two suggestions I think would help,
- Prioritise point selection over the range handle or omit the range handle entirely from this feature or include an option to toggle the range handle feature.
- Include the option to show or toggle the table among the adjacent tool bar.
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [November 17, 2025, 9:04am UTC](https://discourse.paraview.org/t/cannot-select-first-opacity-control-point-with-mouse-in-transfer-function-editor-because-scalar-range-handle-blocks-this-option/17312/2 "2025-11-17T09:04:07Z")
> [@swilliams\_KMT](#):
>
> has been raised a few times over the years but it still persists.
Can you share where it was raised ? Was an issue opened ?
In any case, it indeed looks like an UI/UX bug, same with most-right point.
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### Author:  [@swilliams\_KMT](https://discourse.paraview.org/u/swilliams_KMT)
#### Post date: [November 17, 2025, 11:46pm UTC](https://discourse.paraview.org/t/cannot-select-first-opacity-control-point-with-mouse-in-transfer-function-editor-because-scalar-range-handle-blocks-this-option/17312/3 "2025-11-17T23:46:24Z")
Hi Mathieu,
Thanks for your response. I don’t know if the issue was reported as a bug. Here is a post from 2020 where the user appears to have this selection issue.
> [@Color transfer function: Unable to delete multiple start/end points](https://discourse.paraview.org/t/color-transfer-function-unable-to-delete-multiple-start-end-points/3618):
>
> Hello, this is my first question on the forum. Forgive me if any rules were not followed. So, I added new points to the “Mapping Data” under “Color Map Editor”. I accidentally moved few of the points to the start (i.e. “Data: 1”). Now, I am unable to delete those extra points. (I can delete any points between start and end though) Any help will be appreciated. The following [image](https://discourse.paraview.org/uploads/short-url/hE99djkDxplFDf53VU1L1XzQYa7.png) shows what I am saying.
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [November 18, 2025, 7:50am UTC](https://discourse.paraview.org/t/cannot-select-first-opacity-control-point-with-mouse-in-transfer-function-editor-because-scalar-range-handle-blocks-this-option/17312/4 "2025-11-18T07:50:33Z")
Seems unrelated.
In any case, next step is to open a proper issue on [https://gitlab.kitware.com/paraview/paraview/-/merge\_requests](https://gitlab.kitware.com/paraview/paraview/-/merge_requests) 🙂
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### Author:  [@swilliams\_KMT](https://discourse.paraview.org/u/swilliams_KMT)
#### Post date: [January 23, 2026, 8:58am UTC](https://discourse.paraview.org/t/cannot-select-first-opacity-control-point-with-mouse-in-transfer-function-editor-because-scalar-range-handle-blocks-this-option/17312/5 "2026-01-23T08:58:08Z")
Thanks, Mathieu. Do you need me to open the issue?
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [January 23, 2026, 9:00am UTC](https://discourse.paraview.org/t/cannot-select-first-opacity-control-point-with-mouse-in-transfer-function-editor-because-scalar-range-handle-blocks-this-option/17312/6 "2026-01-23T09:00:05Z")
Yes