foxrever We have several improvement proposals regarding filtering in the tree view. While there are no proposals specifically focused on skin placeholders, the idea of enabling filtering with detailed condition specifications has been on our roadmap for quite some time:
EsotericSoftware/spine-editor533
Other related issues are here:
EsotericSoftware/spine-editor590
EsotericSoftware/spine-editor917
Actually, the feature to select from search results already exists. That question made me realize: you can actually display the Find and Replace window, check Regular expression, enter a period (.) in the Find box to match any single character, then narrow the Types to only Region and Mesh. After that, pressing the Select button will select all region and mesh attachments:
In the screenshot above, Entire project is selected in Scope, but if you change it to Current skin and press the Select button, you should be able to select all region and mesh attachments for the current skin.
