number entry confuses users in topic slider

[prjemian]

When clearing the number in the entry box of the topic slider, or a couple other situations, the text being edited is replaced with a string representing the current known floating point value. That action moves the insertion point and confuses the user.

[prjemian]

• If the test entry widget has focus, do not overwrite the text.
• Keep internal reference of last good value (can get from slider?)

[prjemian]

The problem stems from the code correcting the text value when the user has typed in something not allowed. Perhaps Qt has some helpers that can restrict this entry to white-space or 0.0 - 1.0 floating point range?

[prjemian]

search for Qt4 QLineEdit validator example

[prjemian]

http://snorf.net/blog/2014/08/09/validating-user-input-in-pyqt4-using-qvalidator/

[prjemian]

when text is "0.4" and [backspace] key is pressed, text is re-edited by code to be "0.0" - fix this