eeSchema: hex entry in colour picker won't accept transparency of 0
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# Description
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When entering a discrete 4-byte hex value into the textbox at the bottom of the "Colour picker" dialogue box (this has not been verified for all possible instances where said dialogue box may occur), the R, G and B values are updated as expected, but the vertical "Opacity" slider on the right hand side, is not.
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Further, when exiting the dialogue, the manually entered value is not what is saved/used, but rather the settings of the graphical controls at the time of exit. If the opacity slider would be updated, this would not be an issue.
Perhaps it's just me, but as an old-timer, I'd expect discrete values in a textbox having precedence over graphical representations in sliders and colour-wheels. Anyway, if these two were consistent and updated each other, this wouldn't be an issue.
# Steps to reproduce
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1) Open a property dialogue for any object that can have it's colour adjusted, like a text field.
2) Click in the Colour box to open the Colour Picker dialogue
3) Start typing/deleting in the textbox at the bottom of the dialouge box.
As soon as you do that, you will see the Opacity slider jump up from it's default 0 value to the max 100, regardless of the value of the last byte in the textbox.
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n/a
# KiCad Version
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```
Application: KiCad Schematic Editor x64 on x64
Version: 7.0.2, release build
Libraries:
wxWidgets 3.2.2
FreeType 2.12.1
HarfBuzz 6.0.0
FontConfig 2.14.1
libcurl/7.88.1-DEV Schannel zlib/1.2.13
Platform: Windows 11 (build 22621), 64-bit edition, 64 bit, Little endian, wxMSW
Build Info:
Date: Apr 15 2023 19:18:27
wxWidgets: 3.2.2 (wchar_t,wx containers)
Boost: 1.81.0
OCC: 7.6.3
Curl: 7.88.1-DEV
ngspice: 40
Compiler: Visual C++ 1934 without C++ ABI
Build settings:
KICAD_SPICE=ON
```
issue