How to reproduce:
1. Open the attached project "case_1117293-ToolbarSearchFieldIssue"
2. Open the custom Editor Window by going to Window -> "Toolbar Search Field"
3. Click the search icon of any of the search fields in the window
4. Observe the field widths and separating bar locations

Expected result: a pressed search icon texture is shown when clicking the search icon. Specifying the width modifies the horizontal size of the text field
Actual result: blank rectangles appears instead of the highlighted search icon texture. Changing width only shifts the ToolbarSearchField's separator (black bar texture)

Reproducible with: 2019.1.0b6, 2019.2.0a7
Could not test with 2019.1.0a7 and older (compilation errors due to changed API)

Note: the user has created a workaround for modifying the search field's width which should probably be more easily achievable. The workaround is slightly flawed however when the text field is full as it shifts the clear button more to the right