@Rei_Ayanami: (Are you having a MATERIAL with RELOAD flag, or do you recreate the shader each time that the user changes something?)
At the moment, the shader previews on the nodes are recreated every time you change something in the previous or the node itself. Atm, The final shader is recreated every time a button is pressed (for example the c-key). Then a new effect is created and assigned by effect_load. So no reload flag...

JibbSmart: ty, yes this would make sense(it is also implemented in the source shader editor). It will not be that difficult to implement such a node. However I need to create a lot of other nodes too (dirty job -.-), like texture samplers, swizzle and append nodes, etc. etc.